The Canary Islands are 7 volcanic islands off the coast of Africa. They are but the peaks of several massive shield volcanoes that have grown from the bottom of the ocean over the past 30 million years. The islands are older in the east, and younger in the west. Six out of seven are still active. El Hierro is the most westerly and youngest, it is also the least densely populated (so quite pristine). The next youngest is La Palma, which erupts the most frequently and is said to be the most beautiful. La Gomera, next to the east, is the only one that seems extinct, at least for now. Tenerife, the largest of the seven, has the tallest Spanish mountain; the magnificent and highly active El Teide stratovolcano. Fuerteventura, the oldest (an astounding 30 Ma), is still slightly active, it’s relatively flat and desertic, and also features rare carbonatite lavas which date back to its earliest activity. Lanzarote, the most easterly and second-oldest, erupts infrequently but enormously, after some 20,000 years of dormancy Lanzarote woke up in 1730 flooding a fifth of the island in lava.
Map of the Canary Islands. From Wikimedia by Hansen.
Each volcano has a unique history, but there is one that stands out for me, the one I didn’t mention: Gran Canaria. An island with multiple cycles of activity, ranging from basalt to nephelinite, from rhyolite to phonolite. A shield, a caldera, and a stratovolcano. This is the volcano that did everything. How did it accomplish this? And what remains on the island of this complicated history?
Gran Canaria
Of the seven islands Gran Canaria is the third-largest and second-most populated. It is located in between the older Fuerteventura to the east, and the younger Tenerife to the west. At present it`s 1950 meters tall. Its topography creates a strong climate duality across the island. The mountainous northern heights of the island receive up to over 800 mm of water per year. There used to be a vast laurel forest known as the Doramas Jungle, but this forest has almost entirely disappeared over the past centuries. In contrast to the north, the southern coast of the island gets less than 100 mm/year of water and hosts a desertic landscape. This area has become quite touristic due to its sunny weather and sandy beaches.
Topographic map of Gran Canaria, NASA’s SRTM data distributed by OpenTopography, with places mentioned in text marked.
The shield stage of Gran Canaria
Gran Canaria is possibly the only volcano in the Canary Islands with three stages of volcanism that could be considered akin to the shield, post-shield, and rejuvenated stages of Hawaiian volcanoes. Although they are also quite different. The shield stage however is very clear. This stage is the one where most of the volcano’s volume is erupted, usually within a short interval of time, and where the alkalinity of the lavas is the lowest. Canary Island volcanoes can have very protracted main-building stages. For example, Fuerteventura started to form around 33-30 Ma (million years ago), but it was still producing very voluminous activity by 20-14 Ma, which resurfaced the entire island. The southern part of Fuerteventura, the Jandia peninsula, is entirely made of several hundred meters of lavas erupted at 15-14 Ma. Tenerife could be considered to still be in its main-building stage given the enormous volume that has erupted in the past 3.5 Ma, resurfacing almost the whole island with hundreds of meters of lava, while collapsing repeatedly into the sea and refilling the scarps. Overall Tenerife has been producing voluminous effusive activity since more than 13 Ma ago, there was only a break in activity during ~9.5-6 Ma, so you could say it’s its second shield, and since that cannot happen, then the Hawaiian model does not really work here.
In terms of alkalinity, Canary Island volcanoes are very homogeneous, La Palma erupts basanite, El Hierro erupts basanite, Tenerife erupts basanite, Lanzarote normally erupts basanite, and practically every volcano in the Canary Islands erupts basanite in its main-building stages. So this magma and its evolved products are the main rocks that make up the Canary Islands. Basanite is a magma that comes from the mantle, like basalt, but is lower in silica and aluminum, and higher in a plethora of other elements including magnesium, calcium, sodium, potassium, and others. Such magmas are said to be alkaline because they are richer in the alkali metals, sodium and potassium. However, there are two exceptions to the omnipresence of basanite and its evolved products in the main-building stage of Canary Islands volcanoes, La Gomera and Gran Canaria. La Gomera’s main building stage erupted picrobasalts, while Gran Canaria erupted alkali basalts. These magmas are a little more alkaline than typical subalkaline basalts, but less alkaline than the Canarian basanites.
The presence of less alkaline lavas during its main construction stage is characteristic of the shield stage of Hawaiian volcanoes and some other Polynesian volcanic islands. This can be a sign of intense volcanism, given that alkalinity is roughly inversely proportional to productivity within a given ocean island volcanic province. Added to this Gran Canaria basalts seem to have erupted very rapidly, the oldest shield lavas are dated at 14.6 Ma, while the youngest ones date to 14 Ma. The subaerial basalts probably erupted within several hundred thousand years. This contrasts with other islands where the ages of main-building stage lavas range by millions of years.
It is difficult to know many details from the shield stage due to poor exposure, burial under younger lavas, and erosion. Nowadays the alkali basalts outcrop mostly along a narrow band that runs parallel to the west and northwest coasts of the island, where in places the basalt crops out in precipices up to 600 m tall overlooking the sea. Thin layers of hard rock make up the core of the flows and alternate with weak oxidized layers that are the scoriaceous lava crusts. There is little that can be learned from these piles of lavas other than their age and chemistry. So then how can we know more? To do this we can look at the bigger picture, the size and shape of the island and seamount.
Geologic map of Gran Canaria. Adapted from GRAFCAN and IGME.
The island is, and was, roughly circular, yet another similarity it shares with La Gomera. This means eruptions mostly came from radial fissures. Other volcanoes prefer to erupt through rifts, which is the case of La Palma, El Hierro, and Tenerife, where the rift gives the volcano an elongated or triangular shape. The former shoreline of Gran Canaria can be found 800-1000 underwater. Yes, it sunk 1 km into the sea! This is not uncommon in ocean islands, in Hawaii, for example, a moat of subsidence develops in the seafloor around the volcano in their main-building stage, as they go dormant they continue to subside and the former coast ends up underwater. In the most extreme cases, like Haleakala’s or Puhahonu’s, the coast ends up 2 km below the sea surface where it consists of a break in slope between a shallow, wave-smoothed shelf and a steep talus of pillow lavas and hyaloclastites. Of the Canary Islands, Gran Canaria’s 1 km subsidence is by far the greatest. This subsidence has reduced the size and height of the original island. Towards the end of the shield stage, there would have been a circular island 60 km in diameter, about 50 % larger than present-day Tenerife, and reaching close to 3000 meters above sea level at its summit. Two major landslide aprons bulge out from the southwest and east submarine flanks of the mountain. They are remarkably thick. Originally their top may have been near sea level and they would have sloped gently outwards. Given the major thickness, they are probably polygenetic, with the flanks collapsing into the sea and refilling with lava more than once. At present, above the seafloor, the volcano’s volume is about 26,000 km3, but there must be an additional volume of 15,000 km3 or more of subsided volcanic edifice, landslides, and volcaniclastic material that is filling a subsidence bowl under Gran Canaria. Because of the differences it has with its neighbors, I picture the volcano as being more akin to powerful shield volcanoes that erupt basalts like Piton de la Fournaise or former volcanoes of the Polynesia, than typical Canarian shields.
The shield set the stage for what was to come. It was a strong start to a fascinating story of changing magmas and eruption styles. Perhaps it was the intensity of its early life that paved the road to an intense remainder.
The post-shield stage
At 13.95 Ma a massive explosive eruption covered most or all of the island in pyroclastic flows making a mixed ignimbrite of rhyolite, trachyte, and basalt magmas some 30 meters thick on average. This would be the start of the most dramatic volcanic stage of Gran Canaria. In the blink of an eye, geologically speaking, the composition of the erupted material shifted from full basaltic lavas to a series of silicic ignimbrites. The first ignimbrite eruption is known as the P1 ignimbrite, it starts with peralkaline rhyolite magma which gradually shifts to trachyte and then to basalt, upwards through the sequence. It was a massive explosive eruption, with estimates ranging from 45 km3 bulk volume to 80 km3 DRE, a caldera-forming eruption. It was the first rhyolite to erupt from Gran Canaria, and also one of the last basalts. I think this eruption perfectly represents the transition from what may have been a basaltic caldera system to a rhyolitic one. A shallow magma chamber likely collapsed during P1, this magma chamber may have already existed during the shield stage as a basaltic system and started to accumulate silicic magma due to some change that we can only speculate about. During the eruption, the magma chamber may have contained a mixture of both basaltic and silicic magmas, presumably vertically zoned across the magma body. The thickness of basalt is greater than that of the silicic types in most outcrops, making this one of the largest explosive basaltic eruptions known. This ignimbrite rests conformably on the shield stage lavas.
But P1 was only the first in a series of spectacular eruptions. Caldera-forming ignimbrites started erupting recurrently at intervals of 30,000-40,000 years on average. By 13.36 Ma, some 15-20 ignimbrites had erupted, known as the Mogán formation, intercalated with minor rhyolitic lava flows. The deposits were produced by pyroclastic flows at very high temperatures, which welded the ejecta together, intercalated lava flows are rare, and pyroclastic fall deposits (where pumice rains from a volcanic plume) seem very rare to non-existent. The ignimbrites are widespread, with numerous units being correlatable across much of the island and also in found turbidity currents in the abyssal plains around Gran Canaria. During these eruptions massive fountains of rhyolite and trachyte pyroclasts exploded from caldera fissures near the center of the island, feeding pyroclastic flows that reached 30 km away to the coast while destroying vegetation and animals on their path, they entered the ocean and continued as submarine turbidity currents, spreading across the seafloor as currents of muddy water. Immediately after the eruption, the island would have glowed as if it were on fire, and much of it would be covered in a new veneer of rock-hard ejecta.
The Mogán ignimbrites form exposures of a few hundred meters thick of pyroclastic material within the walls of deep valleys in the southwest corner of the island. Good exposures are found near Puerto de Mogán hence its name. Another nice exposure is found by the west coast of the island, in a series of sharp pyramidal peaks and ridges that overlook the ocean, the highest known as Hogarzales (1060 masl), here there’s a 460-meter thick pile mapped as Mogán Formation in geologic maps. By my count, there are 13 ignimbrites coherent across this exposure, as well as 5 possible additional ignimbrites or lava flows that are discontinuous. The layers are strongly welded and resistant to erosion, the contacts between them are softer and comprise tiny shelves of white tuff along which vegetation grows, making narrow green bands in between the bare rock of the welded ejecta. The pyroclastics lie upon a pile of basaltic lavas, but in a complex manner with visible discontinuities in places. The ignimbrite section also repeats at a lower elevation by the sea. It seems as if the welded pyroclastics cover two plateaus at different heights separated by a steep wall and in turn surrounded by higher areas.
A 460-meter-thick pile of ignimbrites (at least 13 sheets) near Montaña de Los Hogarzales. The lowermost ignimbrite which is dark and somewhat reddish in colour is the P1 ignimbrite erupted at 13.95 Ma. In this area, the P1 ignimbrite is a little over 40 meters thick, with a lower gray-colored half that is resistant to erosion, and an upper part that is black to reddish brown and more easily eroded.
But if there are caldera-forming ignimbrites there must be a caldera right? There is, and a big one at that, but spoiler alert, it may not be what it seems. For a distance of 27 km on the western side of the island runs a semicircular cliff of thick, strongly welded ignimbrites which face towards the sea, and unconformably overlie basalts. This is a curious example of an inverted relief. The ignimbrites are thought to have filled a vast caldera, known as the Tejeda caldera. They are so strongly welded that they look like lava flows. Individual ignimbrite sheets can reach over 100 meters thick, they are dark reddish colored from high-temperature oxidation of iron, are very resistant to erosion, and can have columnar jointing from cooling contraction. The basalts around the caldera were eroded over time, but the caldera-fill held, making what is now a semicircular mesa cut open in the middle by the Valley of Tejeda, a smaller elliptical area inside this elevated mesa where trachyte intrusions are found and which has been eroded down. The Tejeda caldera would have been 17 km wide from one side of the cliff to the other, and it’s thought to be a collapse caldera. But here I differ.
A 2022 article by Montesinos and several additional authors which I link in the references at the end, created a Bouguer gravity map of Gran Canaria. In these maps, you can see differences in the density of rock below the surface, and are very useful. There is something very striking about the map in their article which immediately brought to my mind a shape I’m very familiar with. The map shows a horseshoe-shaped area of high-density material surrounding the center of Gran Canaria on the west, and a U-shaped area of low-density material open to the east. This reminded me of landslide shields, a term I personally use to think of volcanoes where the summit area has a semicircular caldera that is open to one side, like for example Tenerife, or Piton de la Fournaise. There are submarine landslide aprons located next to these U-shaped calderas, which correspond to lava fill that slides away into the sea. I think the Tejeda Caldera is in fact a landslide caldera, open to the east, where a vast submarine apron of volcaniclastic material fills up the area between Gran Canaria and Fuerteventura. It would be some 17 km wide, 40 km long, and possibly over 1 km deep, being buried under younger volcanics of the rejuvenated stage on the eastern half of the island. Tejeda would be filled with low-density silicic rocks from the caldera stage and that is why it shows in the Bouguer gravity map.
But a collapse caldera is needed, right? No problem, there is a better candidate for a collapse caldera. The Valley of Tejeda forms a smaller elliptical area inside the Tejeda Caldera, 12 km long and 5-9 km wide, where many trachytic intrusions are found, including hundreds of cone sheet intrusions, concentric sheets of magma that intrude from a magma chamber in a manner akin to the petals of a flower. Cone sheets concentrate within the smaller elliptical area. Similar cone sheet intrusions are typical of other intraplate calderas where they follow or surround the caldera rim. The seaward-facing cliff of Gran Canaria, the rim of a larger caldera, doesn’t have cone sheet intrusions, and this to me suggests that this is not the collapse caldera, further supporting a landslide origin. Not to mention that a caldera 20 km across like most articles suggest would likely produce large-sized VEI 7 eruptions, and not the VEI 6 events that seem typical of Gran Canaria. If there had been eruption-driven collapses these would have disrupted the intracaldera ignimbrite layers, which, although inclined in places, remain coherent across the high mesa-like area (no faulted layers). So the collapse caldera is smaller and nested inside the larger U-shaped landslide caldera.
This inverted relief, not of a collapse caldera but of landslide headwall, is one of the most special landforms of Gran Canaria. Hydrothermally altered tuffs of reddish and greenish colors are often seen along the base of the headwall, found at the contact with the shield-stage lavas, and sometimes interbedded between the ignimbrites. There is a particular location named Los Azulejos, a small valley carved into the headwall, found along the road that connects Mogán to La Aldea de Sán Nicolás, where white-colored unconsolidated volcanic tuff is in places altered to green and red-colored layers. The tuffs lie on top of the basalts from the shield stage and are interbedded with oxidized dark red welded ignimbrites, waterfalls jump over the welded ignimbrites and cut into the softer tuff. The tuffs and the welded ignimbrites dip inwards towards the caldera and were likely emplaced upslope against the landslide headwall. For a distance of 4 kilometers to the northwest of Los Azulejos the greenish tuff remains visible along the contact with the basalt. It is overlain by a ~350-meter near-vertical drop comprising 10 strongly welded ignimbrites. Towards the center of the cliff lies Los Hornos Mountain towering another 250 meters over the cliff with additional ignimbrites or lava flows (possibly belonging to the later Fataga Formation) that feature columnar jointing and are enveloped in a pine forest, absent at lower elevations.
10 oxidized ignimbrites which ponded against the former headwall of a massive landslide can be seen northwest of Los Azulejos. The dark color can be an indicator of the very strong welding of the pyroclastic material, as opposed to bright-colored ignimbrites. Along the base of the pile, green-colored altered tuffs can be observed, in places where the soil has been stripped away, altered pyroclastic material.
Along the headwall of Tejeda Caldera, east of Los Azulejos, the view gets interesting. In the background, three ignimbrite sheets rest uncomformably on top of a pile of shield stage basalts. These ignimbrites flowed up-slope into the walls of the caldera. In the foreground, the contact between two ignimbrites is cut by a road. The lower ignimbrite turns white towards the top, presumably due to being less welded, a very thin contact of gravel and soil separates it from the next ignimbrite eruption.
The colored tuffs of Los Azulejos are dated with precision to 13.29 Ma, which is younger than the uppermost Mogán ignimbrite (the 13.36 Ma Ignimbrite F). One of the welded oxidized ignimbrites under Los Hornos Mountain is dated at 13.04 Ma. This sequence is called the Montaña Horno Formation and because of the few ages available not much is known in detail about it. It is chemically transitional between the preceding Mogán Formation and the next stage, the Fataga Formatión.
The Fataga Formation is the final stage of caldera volcanism at Gran Canaria. Unlike the earlier Mogán and Montaña Horno formations which were almost exclusively ignimbrite eruptions, the Fataga Formation erupted important volumes of silicic lava flows along with ignimbrites, fallout tephra deposits, and debris avalanches. Magma composition increased in alkalinity from rhyolites and trachytes in the preceding formations to trachytes and phonolites in the Fataga. This formation is best exposed over the southern side of the island, around Fataga. Two to four ignimbrites locally overlying the Montaña Horno formation erupted 12.43-12.33 Ma followed by phonolite lava flows to a total of up to 200 meters in thickness. 6 or more relatively thin ignimbrites erupted in the interval 11.9-11.36 Ma. A final stage of mostly lava flows and some explosive eruptions produced a thickness of up to 500 meters near Fataga, which also crops out in many places over the north of the island as silicic lava flows, lasting from 10.97 to 9.85 Ma. Some three final ignimbrites erupted between 10.40 and 10.19 Ma, which were the last caldera-forming eruptions of Gran Canaria.
By the end of the Fataga Formation, it is thought that more than 1400 km3 of silicic pyroclastic and lavas, including some 30-40 caldera-forming ignimbrites, had erupted. This could be considered as the postshield stage of the volcano, given that Pacific Ocean island volcanoes often have a postshield stage where they erupt some silicic magmas and increase in alkalinity. However, I don’t know of any cases where Pacific volcanoes did caldera-forming ignimbrites. In fact, Gran Canaria’s activity has the largest volume of silicic volcanics known on any oceanic island. The alkalinity of Gran Canaria increased during the Fataga Formation but still remained slightly milder than is typical in the Canarian magma. Nonetheless, the eruption rates were much lower than during the shield stage.
The post-erosional stage
The volcanism of Tenerife and Gran Canaria faded around the same time, about 9-8 Ma. During this time Gran Canaria underwent deep erosion and there was little to no volcanism. Both volcanoes returned to activity around the same time too. Around 6 Ma Tenerife reactivated with the construction of the satellite Teno volcano. Gran Canaria follows at 5.5 Ma. Eruptions intensified around 5.1 Ma. Fluid fissure-fed basanite lavas resurfaced areas of the central and western island over the next 1 million years (El Tablero Formation).
During 4-3 Ma there was a curious interval in the history of the Canary Islands. La Gomera and Tenerife, which had shared protagonism in the 6-4 Ma period, went inactive. La Gomera’s activity died out at about 4.2 Ma. Tenerife which was focused on building its second satellite shield, Anaga, went dormant around 4 Ma. The central shield of Tenerife that erupts nowadays did not activate until around 3.5 Ma, and La Palma would not start to form until around 3.1 Ma. For a brief interval, Gran Canaria may have been the focus of activity in the archipelago. Roughly coincident with this time Gran Canaria entered a second explosive climax in its history.
From 4.15 Ma to 3.5 Ma it was the height of the Roque Nublo cycle. Powerful explosive eruptions produced lithic-rich pyroclastic density currents, which were channelized through valleys, reaching the coast of the island up to 30 km away. Debris avalanches filled valleys to the south. Mudflows built up in the area of Las Palmas de Gran Canaria, by the northeast coast. At the same time, effusive eruptions from issued radial fissures, the lava flows are intercalated with pyroclastic flows, and pumice fallouts from plinian eruptions. Explosive eruptions were extremely energetic but also very different from the 14-10 Ma ignimbrites. Roque Nublo pyroclastic density currents are non-welded which shows lower temperatures when compared to the Miocene ignimbrites, they also also remarkably high in lithics, having 35-55 %. Lithics are fragments of rock from the walls of the conduit that are ejected along with the magma. The eruptions must have been very gas-rich to incorporate such a large volume of lithics into the eruptions, so some authors think they were hydromagmatic. I do think there is another option though.
The magma that erupted during this cycle was unusually alkaline, the more evolved magmas of the Roque Nublo cycle plot between tephriphonolites and foidites in the TAS diagram, with lower silica and higher alkalis than usual trachyphonolitic evolved magmas of the Canary Islands. With increasing alkalinity, the gas content tends to go up. Added to this there is no clear evidence of a shallow magma chamber that collapsed during the eruptions, and the magmas are not fully evolved having around 2 wt% magnesium oxide, compared to contents of 0.5-0 wt % MgO in the postshield ignimbrites. I think it is possible that mildly evolved tephriphonolite-foidite magmas rose straight up from the mantle, 15 km deep, carrying huge amounts of CO2 and H2O volatiles that decompressed into spectacular plinian explosions and pyroclastic density currents. The expanding gas gouged out rocks from the walls of the conduit which were ejected along with the pyroclasts.
The pyroclastic density currents of Roque Nublo consist of breccias made of angular clasts in a matrix of ash. In the highest parts of the island, these breccias are up to 500 meters thick and they have eroded into fanciful crags, ranging from sheer drops to rock needles, ridges, and flat-topped rock formations. Some vertical walls of up to 250 meters tall are made of massive, uninterrupted breccia. One of the rock formations, Roque Nublo, gives name to the cycle and is a very touristic location, a curious rock pinnacle perched above the Valley of Tejeda. The origin of these pyroclastic density current breccias may have been a 1.5 km wide circular structure near the center of the island in an area known as Andén del Toro, from which post-erosional aged dikes seem to radiate, perhaps the remnants of a central conduit, the center of a polygenetic pyroclastic cone or shield, a sort of stratovolcano.
To the left lies the picturesque rock formation of Roque Nublo. To the right Risco de la Foguera is perched atop a cliff. More to the right is the lonely rock pinnacle of Roque Bentayga. All of these rock formations are sculpted into the breccia-like pyroclastic density currents of the Roque Nublo cycle. In the background, towers El Teide volcano in the island of Tenerife. Photo by Javier Branas from Wikimedia.
This chapter of Gran Canaria’s history gave rise to yet another series of crags but of a different origin, plugs of tephriphonolite-foidite. Phonolitic plugs are some of the most peculiar volcanic landforms on Earth, like Devil’s Tower, Pico Cao Grande, or the rock needles of Ua Pou. Gran Canaria’s are not as prominent, but still noteworthy. To me, the most striking of the necks is 3.7 Ma Risco Blanco, a 400-meter-tall intrusion cutting through the Roque Nublo breccias. It’s likely that these subvolcanic intrusions were associated with monogenetic silicic volcanism, conduits to lava flows, lava domes, or maybe tuff cones. More of these intrusions, the Tenteniguada volcanic necks, formed around 3.11-2.7 Ma. Tenteniguada seems to have been the last spurt of evolved volcanism on the island
Risco Blanco, a tephriphonolite-foidite volcanic plug that is nearly 400 meters tall and 400-500 meters wide. The wall behind it is made of breccia-like pyroclastic density currents. It is dated at 3.7 Ma, during the peak activity of the Roque Nublo cycle.
Mafic volcanism was continuous during and after the silicic volcanism. Around 3 Ma, a “voluminous” phase of nephelinite volcanism started. Nephelinite lavas erupted along a NW-SE rift cutting through the island, with the dikes showing a slight radial pattern from Anden del Toro. These lavas erupted from cinder cones and covered much of the northeastern side of the island in lava, thickest along the rift where in places there are more than 400 meters of lava flows. And I say voluminous because it’s not every day that you find large amounts of nephelinite. The lavas erupted from Gran Canaria during this stage averaged 38.5 wt% SiO2, which is very low. Basalt has around 50 wt% SiO2 in comparison. They are nephelinite lavas, which are primitive but more alkaline than basanites, and overall very rare, usually found in small volumes only. This volcanism peaked around 2 Ma ago and started to decline. The activity became very low after 1.5 Ma but continued with sporadic eruptions of both basanites and nephelinites.
During the past 1 million years some eruptions have happened which are mostly very small in volume and inconspicuous. The exception is a group of vents in the northeast part of the island surrounding Las Palmas de Gran Canaria that have produced slightly larger eruptions from SW-NE running fissures. They carry the direction of recent Fuerteventura and Lanzarote fissure eruptions. Here, Montaña de Arucas, in the town of the same name, erupted a small monogenetic shield volcano 420,000 years ago. Another similar fissure happened 150,000 years ago which may have been responsible for two cones some distance apart from each other, Montaña de Cardones near Arucas, and Montaña del Faro in La Isleta. The last known pre-Holocene eruption of Gran Canaria happened 50,000 years ago and formed a 2 km-long row of craters in La Isleta, a small peninsula in the northern part of Las Palmas de Gran Canaria, this eruption is youthful-looking and gained some ground to the sea.
During the Holocene, there may have been a surge in volcanic activity since some 24 volcanic vents have erupted during this time. All of these vents probably do not represent separate eruptions. Eruptions of shield volcanoes tend to open multiple vents and fissures, sometimes offset from each other, and some distance apart. The Holocene eruptions that are radiocarbon-dated form 5 clusters of nearly identical age, so all of the vents could have formed in as little as 5 eruptions. This is a lot considering that the last previous known eruption happened 50,000 years ago. Some think we might be entering a new cycle of volcanic activity in Gran Canaria, although most likely it’s just a small uptick. All of these eruptions came from NW-SE running fissures that are aligned with the post-erosional rift structure of the island, and are perpendicular to the fissures of Fuerteventura and Lanzarote.
The first eruption happened 12600 cal yr BP, just before the start of the Holocene, and produced only a very small flow. Another episode happened 6600 cal yr BP (years before the present) making five vents on a 6 km long line with identical radiocarbon ages, including the cinder cones of Montañón Negro and Caldera de los Pinos. The following three events were closely spaced happening at 3000, 2450, and 2000 cal years BP, and erupted mostly from the eastern sector of the island, each making a number of different vents. The last activity, 2000 years ago, is interesting. While the other eruptions are basanitic, this event produced nephelinite lava. Nephelinite is found in a small lava flow that issued downrift of two explosive maar craters known as Caldera de los Marteles and La Calderilla, all probably formed at the same time. This is the only known nephelinite erupted during the Holocene in the Canary Islands. Another maar crater formed around this time in a different part of the island, perhaps in the same eruption or a different closely spaced event, the Caldera de Bandama maar and the immediately adjacent Pico de Bandama cinder cone. Caldera de Bandama is a circular crater 900 meters wide and 200 meters deep located south of Las Palmas de Gran Canaria. The walls expose pyroclastic density currents of both the Fataga formation and Roque Nublo cycle that were excavated by the explosions. Tephra, which erupted from the Bandama maar, covers 25 km2. I have wondered if this eruption was driven by gas-rich nephelinite magma too. However, I haven’t found any information about its composition. The Holocene eruptions amount to 0.4 km3.
Caldera de Bandama seen from Pico de Bandama. Before us lies an explosion crater excavated into the pyroclastic density currents of Roque Nublo that are exposed in the walls. Scoriaceous lapilli and lithic material ejected by Bandama are layered in the uppermost walls of the crater. I believe this eruption was likely driven by magmatic gasses which violently decompressed from a volatile-rich basanite or nephelinite magma. Image by El Coleccionista de Instantes Fotografía & Video extracted from Wikimedia.
A shield, a caldera, a stratovolcano, and a shield again, the history of Gran Canaria is a fascinating one and is still being written. The island is a legacy of changing eruption styles and lava compositions which gave rise to one of the most complex volcanic edifices on the planet. It perhaps is the maximum expression of a different class of hotspot volcanism that involves multiple volcanic cycles and phases of silicic volcanism. Its landscapes may not be as grandiose as those of La Palma and Tenerife but is a geological wonder and a scientific curiosity.
References
Guillou, H., Torrado, F. J. P., Machín, A. R. H., Carracedo, J. C., & Gimeno, D. (2004). The Plio–Quaternary volcanic evolution of Gran Canaria based on new K–Ar ages and magnetostratigraphy. Journal of Volcanology and Geothermal Research, 135(3), 221–246. https://doi.org/10.1016/j.jvolgeores.2004.03.003
Hoernle, K., & Schmincke, H. (1993). The Petrology of the Tholeiites through Melilite Nephelinites on Gran Canaria, Canary Islands: Crystal Fractionation, Accumulation, and Depths of Melting. Journal of Petrology, 34(3), 573–597. https://doi.org/10.1093/petrology/34.3.573
Montesinos, F. G., Arnoso, J., Gómez-Ortíz, D., Benavent, M., Blanco-Montenegro, I., Vélez, E., Crespo, T. M., Горбатиков, А. В., & Stepanova, M. Y. (2022). Imaging the volcanic structures beneath Gran Canaria Island using new gravity data. Journal of Geophysical Research: Solid Earth, 127(11). https://doi.org/10.1029/2022jb024863
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van den Bogaard, P., Schmincke, H.U., 1998. Chronostratigraphy of Gran Canaria. In: Weaver, P.P.E., Schmincke, H.U., Firth, J.V., Duffield, W. (Eds.), Proceedings of the O.D.P. Scientific Results, vol. 157, pp. 127 – 140.
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Very intresting Thank you! yes Canaries is varied and strange volcanism
Wow so Gran Canaria was an evolved caldera shield long ago that did almost Tambora scale stuff, quite Impressive, alkaline magmas are rarer and formed in smaller ammounts than subalkaline ones so large pyroclastic high end alkaline eruptions are a rare sight
Excellent article anyway : ) If we gets a New eruption it coud be Nephelinite tuff maar, or a cinder cone
Been ar GC a few times with girlfriend and always writes it off as unintresting geologicaly, when in turn Gran Canaria is a monster sized volcano witt an amazing ammounts of magma variation and the possibilty to take home a Nephelinite specimen ( rare magma! ) getting the possibilty to get hands on the Nyiragongo magma without going to DRC 🙂 I guess I haves to go there again and probaly alone as she have tired of the Canaries
And as well as getting the Phonolite thats very rare stuff too. It have a distinct sound when banged ”sound stone”
Thanks Jesper! Gran Canaria tends to go under the radar. It has been a slow discovery for me, from hearing about one or two of its ignimbrites to learning about Roque Nublo, then the Mogán Formation, and finally that it was a powerful basaltic shield that has large amounts of rejuvenated nephelinite. The chemical variation of the lavas (in terms of alkalinity and fractional crystallization) is quite remarkable, the mafic lavas range from alkali basalts to nephelinites which is not unique, however, evolved lavas ranging from rhyolite to foidite in a single volcano is something I’ve not heard of happening elsewhere.
Great piece, Héctor, very complete. Yes it is not as fascinating a landscape as the western neighbours, but that is because it is closest to Africa and quite dry and sandy. Bandama though is phantastic and also greener than it seems on your chosen photograph and has – guess – a great golf court where I used to walk with some golfers being passive myself and enjoyed the scenery.
It is not that astonishing that Réunion and also Mauritius, being closer to the equator at between 20 and 22 latitude (GC 28) are much greener as GC is strongly influenced by the desert Sahara receiving loads of sand when the wind is right.
So GC has a west-African climate nicely modified by the Atlantic Ocean, whereas the Mascarenes being sheltered by Madagascar have an Indian Ocean Climate with also seasonal monsoons.
In fact – while I am getting into this the situation seems nearly comparable, funny, with Madagascar`s last eruption about 6000 years ago
https://fr.wikipedia.org/wiki/Champ_volcanique_de_l%27Itasy
(page not worked out in English)
and younger volcanism further east in Réunion comparable to Tenerife/La Palma/El Hierro.
GC and Madagascar being drier, the outer islands wetter and lush.
(Although the beauty of Réunion has nearly no comparison in the
world and served as background inspiration for the VG Uncharted IV).
What’s interesting here is Mayotte on the other side of Madagascar plus the fast growing underwater mystery.
Anyway, thank you for the brillant informative piece which I will save for further travel to the area.
to be added: Latitudes of courth north vs south (Mascarenes)
Canaries also sits in a cold seacurrent that limits evaporation and cloud formation if you cannot be tall enough for ortographic rainfall, warm air above a cold ocean .. and you gets desert conditions, thats why Furvertuventura is a wasteland, had a warm seacurrent been present the Canaries may have almost been as green as the Azores, but Azores is further north into the storm cyclone zones so there is that too. Still even the green sides are not as green as the equator, but the laurel forests are stunning
Hawaii is green because its ortographic rainfall, it too woud be rather barren without tall volcanoes, but the sea in Hawaii is much warmer than in the Canaries
And I am going to try to write a VC piece on a Nyiramuragira thing .. : ) Im feeling so slow minded .. althrough you have alot more article experience than I do.
When it comes to Gran Canaria I remeber last time walking around the rim of some explosion crater with my girlfriend, huge and deep and located near the largest city there Pico De Bandama area .. gigantic explosion made that pit
That must have been Caldera de Bandama, it’s close to the main city of the island, Las Palmas de Gran Canaria. Although there are a couple of others too that are more eroded or smaller. It is about 2000 years old.
Thanks Héctor for a fine narrative! A fine and interesting story told over 30 million years. I especially like alkaline magmas since I’ve worked with nickel and rare earth elements, which can be associated with such critters.
I do have a question about the very youngest phase. How does carbon dating work for lavas? My basic understanding is that 14C dating is based on the time since a sample has been in equilibrium with atmospheric carbon dioxide isotopic ratios, since the 14C mainly comes from cosmic ray irradiation of CO2. So that when a sample is no longer in equilibrium with the planetary atmosphere the 14C decays, and the proportion of 14C vs the equilibrium level can be related to age via the half life of the isotope.
But a magma has been, by definition, subterranean, so all the 14C should’ve decayed away. Thus I can’t understand how carbon dating would work on a lava deposit, since the innate carbon composition should have zero 14C in it. Is it perhaps the vegetation associated with the erupted lava? (Maybe I’ve just answered my own question. 😀 But I’d be interested in any comments.)
Its done on charcoal under the lava that is assumed to be created by it, although this is not always reliable. Generally it is fine though, especially if the trees are resistant to burning so unlikely to be burned in any other way, which is the case for many volcanic island vegetation.
Thats right, trees are pretty resistant to fire and rarely gets fully destroyed even during a large forest firestorm, due to they have low conductivity and often stores tons of water in the wood trunk.
Lava is very dense indeed and a bit hotter than a forest fire, so is the only thing that really destroys trees in nature firewise with its hot very high density medium as it is. Still large trees can stand for hours in pahoehoe flows before they topple over and burn through. Short lived very thin lava flows like at Nyiragongo and some Kilauea examples may not destroy a tree, just kill it .. leaving dead black skeletons in a rock flood with their trunks encased
That is correct. There is no carbon in lava that can be used for carbon dating. Charcoal in or under the lava gives the age of whatever it is that was burned. That is the age of the tree though, which will beholder than the lava that burned it. You need a variety of pieces from different trees , and the age of the lava flow will be a bit younger than the youngest measurement. (In practice each measurement comes with an uncertainty that may be 100 years or so, so it is a bit more difficult than this.) Of course it only works for lava flows no older than a few tens of thousand of years. For ages of million years, other radioactive elements are needed and they do occur in the lava.
Btw, I appreciated your piece about Campi fl., but was taken down by events.
Pahoehoe flows who are very fluid dense tends to preserve plant root carbon in soil bit down since oxygen cannot get there .. If the soil is very deep
Aa flows of are vesicular allows oxygen to get down into the soil below and usualy incenirates buried soil carbon below them. Thats at least what USGS says in some papers. In the lava itself No organic materials can make it, only animal bones survive that calicium fyed like in a cremation
But trees can material wise surivive short lived thin lava flows and leave carbonated stumps behind or dead trees standing
Giants ( If this photo pops up )
Lots of volcanoes in Africa so always a possibilty that a mega baobab gets engulfed one day in the rift 🙂 One can always imagine how souch a massive beast like this woud put up against a lava flow with the 1000 s of tons of water they hold, the lava woud winn but how much depends on size and lenght and souch of the eruption
A lava flow will destroy anything organic being a very hot very high density enviroment, each lava flow also stores heat very well, a natural furnace, so perhaps even a Giant Baobab tree is easy prey from a lava flow and very much so If its long lived.
But a short lived lava flow probaly woud not destroy a tree as large as this, the thicker lava flow is the longer it stoores destroying heat longer than thinner ones
https://monteverdetravel.com/6000-years-old-baobab-tree-in-senegal/
Carbon 14 usually originates in the atmosphere. The sun rays hit Nitrogen 14 atoms which lose their proton. Next chemical element below Nitrogen is Carbon, so N14 becomes C14.
Volcanic CO2 has no atmospheric CO2 and should by this stay C14 clean.
I like the mixed eruption types of alkaline magmas. They more often than mafic magmas do explosive-effusive eruptions like La Palma 2021 or Vesuvius 1944.
Basanite seems to partition gas and melt plus having a naturally high volatile content, so it is really good at doing mixed eruptions. The event 6600 years ago at Gran Canaria made an explosion crater where gas just blew away the ground (El Fondo), a vent that is in between an explosion crater and a cinder cone (Caldera de los Pinos), a typical cinder cone with tephra rich lava fountains (Montañón Negro), and four places where lava gushed up of the ground making spatter cones or no cones at all.
Usually radiocarbon dating comes from charcoal under the lava, assumed to have been formed by the lava flow. Mauna Loa, for example, is very well studied with radiocarbon and the results of multiple determinations on the same lava flow tend to match relatively well. It can also come from dating the soil under the lava which contains organic material, but depending on the soil the age can be too old. Charcoal under tephra deposits can also be too old since it may come from earlier fires. Sometimes a whole tree trunk can be dated, embedded in the lava or more commonly in pyroclastic density currents or mudflows, and then it can be calibrated with the known variations in the carbon isotopic composition of the atmosphere to get a very precise date of the tree’s death (supposedly during the eruption).
Oxygen poor enviroment is needed too, that typicaly exist inside lava flows as well, but because lavas very high density its uncommon for any plant or dead animal to end up inside a flow .. just burning on top of it
Well Aa flows do bury stuff as well as pahoehoe but taking about flow core
Tephra pyroclastic sheets are also similar if welded or dense of course
Quite true, I’ve seen those Kilauea Iki videos with the trees like torches floating on the lava. I think the charcoal must usually come from roots rather than the plant itself.
Apart from Radiocarbon there is a variety of alternative possible radiometric dating: https://en.wikipedia.org/wiki/Radiometric_dating
F.e. Uranium-thorium dating for timespans until 500,000 years
Thank you, Héctor! I thoroughly enjoyed reading your article.
Thanks, Clive!
I found this series today. It investigates a possible (key word) impact in the Mediterranean around the start of the Holocene which basically pressure washed the coastline of Greece, Albania and Italy, and flooded over large parts of the low lying Sahara.
Honestly I really dont know how to interpret this, it is so mind boggling that it sounds impossible, but then so do a lot of natural phenomena until someone does take it seriously and investigates. And similar studies that began with similar outlandish hypotheses lead to the discovery and confirmation of the Burkle crater. It is completely still a hypothesis at this point but there is way more investigation than it just being some pseudoscience stuff made up to explain Noahs Flood or Atlantis.
https://www.youtube.com/watch?v=ZKUPPEJjE0A&t=163s
I guess, it would also be rather hypocritical of us to call this out too with some of our own hypotheses regarding volcanism 🙂
https://en.wikipedia.org/wiki/Burckle_Crater
Seems not everyone is in agreement whether it is a crater, but at that location it can really only be an impact or something volcanic, either option is interesting 🙂
Searched those coordinates, looks to me like it’s probably a funny shape made by the ridge volcanoes.
That was my feeling too
Large impacts are very rare. Any claim for one within historical periods should require very strong evidence. Most of these claims can be safely ignored. For Burckle, the evidence of it being an impact is very slim. It is sitting on a spreading ridge where the rocks are young. The chance of this being an impact feature is close to zero. And remember the Hiawatha crater in Greenland where the supposed age of 10,000 years turned out to be 50,000,000 years.
Its only in the spreading axis where eruptions are frequent and at souch a very slow spreading ridge, they will not be very frequent at all per 100 km of it
Eruptions are near continuous at the spreading axis, but you mean large ones. Still, they are much more frequent than impacts! But it is far from clear that that is a crater. The maps shows an incomplete and broken ridge, not a round structure but an intermittent ‘u’ shape. It could easily come from accidental alignments, or it could be a collapse feature (it is sitting on the outer southwest slope of the spreading ridge). There is a lot of wishful thinking in calling this an impact (or any type of) crater.
I know it is slim but it is this sort of curiosity that leads to new science being done and new things being learned. I watched a few more of his videos and OzGeography might be dancing with the edge of pseudoscience here but his other videos are all very solid subjects. In my short time on this planet I have come to be a bit resentful of the current scientific field, its often unnecessary conservatism, the way it reacts to boundaries being pushed. Modern science would treat Galileo the same way the church did in his time.
Even if these craters are not as such, what actually DOES happen if a major bolide hits the deep ocean? Its not like the idea isnt known, chances are way higher an impact actually does happen on the abyssal plain than anywhere else really, but as far as I know the only thing ever stated is that a wave would be generated, and this has never been simulated. Or what would actually happen if a megatsunami of hundreds of meters height and the full depth of the ocean were to hit a low lying continent without a mountain barrier? A bolide that can make a 30 km crater is way more powerful than even half of Mauna Loa falling into the ocean and would push the entire depth of the ocean out of the way at the same time, which is very different from the waves in fjords like recent megatsunamis have happened in. Impact waves would be like subduction zone tsunamis but point sourced and with far larger maximum heights.
Imagine the waves If Chicxulub hit the deepest trench back then 🙂 Big waves for soure and No impact crater to find today
I doubt the 11 km deep ocean woud muffle any of the catastrophic effects from the impact
Chicxulub asterpid by utself was bigger than tbe depth of the ocean so no it is very unlikely the deep ocean wpuld damp the impact. But, apparently the location it hit and the geology could have been important to the K/Pg, lots of anhydrite in the rocks. Its the same reason El Chichon made such a climate impact for a VEI 5. So if Chicxulub hit in the deep ocean perhaps the variety of dinosaurs around todat might have been greater although probably still with a mass extinction. I guess, maybe some birds would have teeth today 🙂
There are simulations of ocean asteroid impacts. A 25-km crater would normally require a 1-1.5km asteroid, large but not extreme. However, if they impact water they lose a lot of their energy in the water. One paper mentions that such an asteroid coming at 20 km/s (faster than average) comes to a halt in 0.7 sec, meaning a distance traveled of 7 km. Assuming a 5 km deep ocean, that reduces the impact quite a bit. A vertical impact still gives a crater, an angled one does not. The tsunami is extremely, 1km high locally but falls of faster than normal tsunamis: at 1000 km it is down to 10 meters. The problem is that this gives a crater that is much smaller than the Burckle feature, but if you make the asteroid larger the crater becomes much larger. It is hard to get an oceanic crater of this size. Interesting, the asteroid of course vapourises a lot of water but this become mixed with its own debris. Expect very dirty rain for a while.
Its still a field that is not well studied as far as I can see. Composition of the impactor is also important, if a metallic asteroid was involved then it will be dense and not as easily stopped by the ocean. If it is loose then the thing will probably just blow up before even reaching the solod seafloor, so not making a crater at all but potentially making a much larger wave even.
There is also the unknown variable with impacts that comets bring. Comets falling from the Oort cloud are undetectable and would hit at immense speed, faster than any asteroid. My impression is that impact frequency is based on crater cpunt but if it takes a large impact of a solid object to actually even make a crater in the deep ocean then that is 2/3 of the candidates basically gone without a trace.
It seems that even the existence of the Late Heavy Bombardment, which was always used as a kind of loose calibration for impact frequency, is very uncertain at this point.
It would be good to see some detailed seafloor mapping of the Burckle crater, and sampling of the rocks.
Comets can hit Earth at 65 km a second .. even a small fragment the size of icon of the seas woud be catastrophic as seen with the Jupiter impacts like 2009
That velocity is very rare. The minimum velocity is 11km/s. The most common velocity is a few km.s higher for asteroids and around 30-40 km/s for comets (but comets are less massive and more likely to break up in the atmosphere). The chance of something hitting us at higher velocity is smaller than that at lower velocity because of an effect called gravitational focussing. At high velocity, objects have to get much closer to Earth before they can hit. At low velocity, more distant encounters can lead to collisions. The simulations used 20 km/w which is already on the high side for an impact
Regarding impacts the rarity of high velocity impactors may be a bit higher than traditionally assumed if one accounts for tidal disruption due to the Sun and or Jupiter as those can create a family of objects which spread out increasing the likelihood that one or more might collide with Earth. Shoemaker Levy 9 was an example of this type of gravitational disruption. However in terms of a worst case scenario would be a large Sungrazing long period comet.
Though on longer timescales we do also know that stars pass within the boundary of our Oort cloud and thus during such a close encounter we will be within the boundary of their Oort cloud, thankfully objects in these environments far from the star are in low densities since they are spread over such a large volume however if one does interact it would appear to be on a hyperbolic trajectory and thus going very fast. The close encounter with Gliese 710 in 1.29 million years will be a situation where this could be expected to be possible as that star will pass deep into our own Oort cloud while being a more massive K dwarf star or around 0.6 M_Sun.
And as for composition like chad said its quite important and even more complicated for example for loser rubble pile asteroids many of them are likely really Earth Grazers which break up in Earth’s atmosphere leading to them colliding with the atmosphere destructively in a airburst event, for a more metallic asteroid its even possible that such an Earth grazer can survive its encounter while retaining enough of its celestial velocity to be able to escape back into a now changed solar orbit in essence creating an airburst impact without actually impacting now being in a less energetic(i.e. less eccentric) Earth crossing orbit. In this scenario based on models its possible such a metallic asteroid could survive several encounters before it finally loses enough momentum to finally collide with the planet proper. It has been suggested that Tunguska may have been one such grazing encounter with a metallic asteroid since there is no identified crater or large meteorite fragments, as would be expected for an airburst disintegration, and while we do have evidence for metal rich dust of extraterrestrial origin its not enough to be any more than part of the thin outermost layer lost during passage through the atmosphere. If this is the case then we need to know since such an object will one day cross paths with the Earth again. Another possible fit for Tunguska observations however would be a stony metallic asteroid which would based on observed trajectory of the airburst have eventually crashed to Earth somewhere in the Northern Pacific making verification difficult to say the least point is that for an intermediate object like a stony asteroid the likely outcome is such a rock would eventually crash down into Earth as its kinetic energy burns up as enough kinetic energy would be lost due to ablation with the atmosphere and possible fragmentation not unlike what happened with the Apollo group asteroid which caused the Chelyabinsk event.
However as asteroids appear to be quite complicated in their structures it is quite probable other outcomes are possible.
And major impact events don’t need to happen on Earth to affect us as is exemplified by the Ordovician meteor event where 468 ± 0.3 Ma two large asteroids collided out beyond Mars in the main asteroid belt leading to the break up of the 150+ km across L chondrite progenitor. Due to conservation of angular momentum the resulting collisional cascade would have fallen inwards over time leading to a large spike in fossil meteorites and meteoric sedimentary grains as well as a spike in moderate sized craters over the next few million years and likely contributing to the cooling during this period as based n the observations of similar collisions around other stars by transit exoplanet missions such as NASA’s Kepler and TESS observatories we should have seen around a 1% decrease in sunlight reaching Earth for several tens of millions of years.
For an even bigger parent body the effects would no doubt be even more extreme.
At Jupiter there is also that gravity well as well, but comets speeds ut immensely as they go close to the sun too
They can reach speeds of 45 km/s at the orbit of the earth. The relative speed with respect to us depends on the direction they travel.
Albert imagine the cometary impact speeds on Brown Dwarfs that are many times denser than osmium in overall density some incredibley high gravities at the cloud tops.
atmospheric entry on these objects are stuff of nightmares.. remeber even Jupiter is a very difficult atmospheric entry
Jupiter have insane atmospheric entries 60 km a second or more depending on angle towards the planet or relative orbit, seeing what some oil tanker ship sized fragments that was as dense as snow of Shoemaker Levy 9 did on Jupiter is pretty terryfying.. the 2009 impactor was only 300 to 500 m wide and left a firecloud the size of the pacific ocean…
Woud be fun to see the effects on Jupiter of a Chicxulub sized impactor and that it did not break up, the energy in jovian impacts is tremedous really. And Jupiters uppermost atmosphere where these behemoth explosions happens is incredibley tenious, so that says something how fast they move
Frequent eruptions woud not be that common per km at least in a slow spreading ridge I think, its pretty weak volcanism .. many pillow flows are sediment covered
Faster Spreading Ridges have much much much higher rates of volcanism than these ridges
The avarge slow spreading ridge is probaly much less frequently erupting than Reykjanes Penninsula per similar sized area, and Reykjanes thats have a hotspot motor and that one is probaly not always going unless its a rift cycle like its now ..
Atlantis was predominantly a philosophical utopia (f.e. Marx’s ideal communist city) to develop an ideal world. I don’t think that Platon really applied to a historical event from his personal view.
The most important cultural event was the Minoan eruption of Santorini (1700-1600 BC) that destroyed the first important European civilization. I suppose that this is the only significant Atlantis event that occured since the origin of the oriental high cultures.
The story of Noah’s Flood originates in Mesopotam. There no Mediterannean Tsunami would have mattered physically. There desastrous floods of Euphrat and Tigris would be the main threat, and I’d assume that the experience of such a flood inspired the story of Gilgamesh and Noah. The origin of Judaism/Israel is strongly linked to the ancient cultures of Mesopotam and Egypt.
I always assumed Atlantis was a very stylized recollection of the Minoans, or if not then one of their predecessors perhaps who were lost in name but not in memory.
Mesopotamis was the first case of writing but not necessarily the first civilisation. Still it was a major hub of its day and woulf have attracted people far and wide, probably including many from Europe and the Mediterranean. The flood myth is very widespread, the biggest event might have been the reconnection of the Black Sea, sometimes visioned as catastrophic but more likely fairly gradual, but even if it was gradual it would have been obvious over human timescales and rather dusruptive, and potentially still dangerous. This was all happening at the same time as Gobekli Tepe and nearby ruins were already well established and depending on the date and what hypothesis is followed they are even genuinely old even at this point, so people around were already sophisticated even if they didnt write or use metal tools get. The Black Sea flood is heavily debated but what is not debated is that the area had a lot of very shallow plains that would have been inundated greatly by even moderate rise, and even today the area is very fertile, it would have been important way back then too.
That and, well, all rivers flood and we are naturally scared of deep water yet drawn to it out of necessity.
The Noah’s thing was *certainly* plagiarised from ‘Gilgamesh’ but, IMHO, there’s a plausible candidate for Atlantis on the North-African Atlantic coast. IIRC, it is coastal triangle between Atlas and Anti-Atlas mountains, almost inaccessible by land. Implication, they were obligate sea-farers.
https://web.archive.org/web/20201124060405/http://asalas.org/doku.php
There’s lots of Neolithic stuff, wells, irrigation channels etc etc. Then, just abandoned. Perhaps the mountains’ snow-caps shrank too much ? Perhaps a quake deranged the water-table ?? IIRC, one of the S-American peoples found their irrigation canal network ruined by a post-megathrust quake’s tilt…
On a more serious note, I must wonder why the Canaries *are* where they are. Unlike the Azores or Iceland, they do not straddle Mid-Atlantic spreading. Unlike several S-Atlantic off-ridge islands, they do not straddle faults or hot-spot tracks. They seem too far from Tibesti Massif and the Med’s complex subduction….
“I must wonder why the Canaries *are* where they are.”
That is an unanswered question among many unanswered questions of volcanism. That part of the North Atlantic is a mess, you have Cretaceous carbonatite volcanoes in Western Sahara, and large Cretaceous syenite (intrusive trachyte) plutons in Portugal. A very important province of extremely alkaline volcanism, including carbonatites, ultramafic magmas, and such is found around Montreal in Canada which is also Cretaceous in age and was back then right next to Portugal. Many ocean island groups have developed in the ocean in between since then, the New England Seamounts, Bermuda, Madeira, Great Meteor, Azores. And of course the Canary Islands and Cape Verde which might well be the most productive basanite-phonolite-nephelinite-carbonatite volcanic provinces in the world right now together with the Rungwe and Virunga volcanic areas of East Africa.
The same tsunami could quite easily have been caused by a large earthquake in the Aegean megathrust or by flank collapse of Etna, which we know has caused a tsunami as far as Lebanon. We know that there have been 2 caldera collapses on Pantelleria also.
A giant essay with huge amount of working hours before! Gran Canaria should be named real vulcania island since it has done nearly everything volcanoes can do.
Should we view Gran Canaria as a complex volcano? Does it share the characteristical elements which are typical for complex volcanoes?
How did the lava flows 2000 years ago look like? If the magma/lava was very gasrich that it produced explosive crater/maar eruptions, how could magma reach effusively the surface?
Nephelinites are so very gas rich If they ascend directly from the mantle that they usualy blow up into tuff cones or maars, and probaly so during the startup phase of a Nephelinite cinder cone eruption, later you gets tall La Palma like eruption fountains and cone formation when gas content dropped, the magma itself is very fluid althrough the high gas content often means it blows up at start. In La Palma it ascends directly from the mantle as postshield erosional stage does not have any shallow chambers, the magma loses gas as the eruption progress and some eruptions had enough magma for more than just a maar
Nyiragongo is a rare example of quite prolific Nephelinite production and allows that magma to accumulate into preexisting shallow resovairs and degass. And probaly is why Nyiragongo does not do subplinian eruptions anymore.
But Basanites woud be more prone to make flows and cinder cones with less gas content and higher avaible magma budget
So would you guess that the lava flow 2000 years ago was fluid Pāhoehoe lava like Nyiragongo or La Palma?
The size was small and the age has supposedly altered/eroded the lava flow a lot. I have the impression that the recent eruptions remind to Honululu’s rejuvanted eruptions
Probaly is a channel feed Aa flow from a small fissure. Viscosity probaly No diffrent from Halema’uma’u althrough some really primitive Nephelinites coud perhaps be more fluid than thoelitic mantle basalts due to their low Sio2, monogenetic Nephelinites ascend quickly from mantle depth, so they should be very hot, and have very low Sio2. Nyiragongo have a polygenetic Nephelinite so probaly is cooler as its stoored in shallow crustal chambers
I think the larger holocene cones are Basanitic as that magma is less gas rich and more common than a Nephelinite that woud be most maar and tuff prone … monogenetic Basanites makes cinder cones, and monogenetic Nephelinites and Melilitites makes maars and tiny flows
This is correct right Hector ?
I’ve checked again the article of the Holocene eruptions on Gran Canaria and they do give the composition for most cones. They are nearly all basanitic in composition, even Caldera de Bandama. The only nephelinite lava is El Garañón, a lava flow immediately downslope of Caldera de los Marteles (for which composition is not mentioned).
Then Im correct 🙂
Thanks Volcanophil!
Well, Gran Canaria has been usually classified as a sort of changing volcano that started as a shield volcano, then a caldera, and a stratovolcano, to then become a shield or volcanic field again. It’s not all the things at the same time but rather changes activity. The shield stage I think was a pretty intense “higher shield” (those that are basaltic and possess shallow crust mafic storage), maybe akin to Reunion or Kauai. Then it shifted to something that you don’t usually find in intraplate oceanic settings a sort of Tibesti-like caldera system but higher caldera recurrence that made rhyolite-trachyte ignimbrites like they were sandwiches. And then you get this weird bimodal volcano with radial effusive fissure eruptions and tremendous plinian outbursts that I’m not too sure where to put it, kind of like Vesuvius (the tephriphonolites are in fact similar in composition to Vesuvius, just sodic instead of potassic). It’s a volcano that had a strong supply for long enough to have multiple lives under different conditions.
As for the Holocene eruptions they seem to partition gas and melt. The explosion craters like Caldera de Bandama, Caldera de los Marteles, or El Fondo did not source lava flows, the lava flows came from cinder/spatter cones or just fissures downslope of the explosion craters:
https://visor.grafcan.es/visorweb/default.php?svc=svcOrtofoto&srid=EPSG:32628&lat=3122960.3873173553&lng=339987.5799187448&zoom=19&lang=es
The same thing happened in the 1949 eruption of Cumbre Vieja, where lava gushed from the side of the mountain without explosivity while Hoyo Negro near the summit blew into a maar/explosion crater.
The reason Canary Volcanoes resembles continetal volcanoes likley also have to do with the very thick and old oceanic crust and litosphere there, magmas are generated deeply and supply is slow and that gives rise to evolved and strange alkaline magmas, looks like GC had a more or less open conduit during its main shield phase when supply was much higher than today, only the crust is diffrent composition in Sahara, but the mantle is the same ultramafic rocks thats source of magma genesis
It seems t be a mix between rift and plume volcanism. Nephelinites have also been erupted at places like the East African rift, Hawaii, in Kyushu and also in the back arc of Canadian volcanism (Wells Gray-Clearwater) according to Wiki.
Clearly it requires a mantle component alongside some partial crustal melting.
Could it occur naturally through a mantle injection into previously erupted layers (re-melting) in a shallower magma chamber, given the time gaps between eruption phases?
Syenites are pretty rare and seem to be associated with plumes/LIPs.
The most important nephelinite volcanoes of our time are Nyiragongo and Ol Doinyo Lengai. Fogo (Cape Verde) is basanite, but borderline with nephelinite in the TAS diagram.
It is a rare magma, but in the past, there have been some really powerful alkaline volcanoes. During the Cretaceous, a number of places around the Atlantic saw extreme alkaline volcanism, particularly in Brazil. The Poços de Caldas volcano, for example, is a VEI-8-sized magma chamber in Brazil that was active for millions of years in the Cretaceous, it has some very alkali-rich phonolites, more alkali-rich than those of Fogo or Vesuvius, and many of its primitive magmas are nephelinite-like, as low as 36 wt% SiO2. Not far from there, in the Alto Paranaiba province, there were caldera systems of carbonatite and a rare silicate magmas, known as phlogopite-picrites, that had around 30 wt% SiO2, kimberlites erupted around these volcanoes and may have very well been the progenitors of the phlogopite-picrites,
Interesting that all 3 of those volcanoes are rather active. Nyiragongo needs no further comment, but Ol Doinyo Lengai is also pretty much continuously erupting now, even if silicate magmas erupting from it are relatively rare nowdays. And Fogo is a quite big volcano too, and erupts a few times a century with fast lava flows and tall fountains. It was apparently continuous for a long time too between the 15th and 18th century, not sure if that is true or not but the cone is young.
Nephelinites and Melilitites are generated very deep down in a metasomatized cO2 enriched enviroment under high pressures perhaps mantle carbon and fluids are at play, But overall its a sillicate magma But a very low sillica one, they also wants a low degree of fractional melting in an original parent mantle source
The Canary islands based on what I can find in the literature seem to be a bit more complicated.
https://www.sciencedirect.com/science/article/pii/S0012821X2200142X
From this paper it should be noted that in at least the case of Fuerteventura where its lack of recent activity means erosion has exposed some of its older layers the magmatic activity activity appears to date back to the Cretaceous with intermittent younger activity much like the other islands just no Holocene volcanism like the other islands. Thus its possible this old age might be unique or it could be that the remain islands have buried any similarly old layers of rock.
The does appear to be some age progression but it isn’t nearly that apparent compared to other oceanic hotspots which seems to be a consequence of the plume interacting with craton edge effects due to the heterogeneity of the underlying mantle, one hallmark of this is that there is a trend of irregular intervals of renewed volcanism in crude models that statistically have somewhere between 20 to 40 million year periods.
Thus whatever is going on here it is very complicated as material is in essence erupting through many tens of millions of years of eruptive products. I suspect the preferential sustained nature of magmatic activity on these islands likely involves these volcanoes lying along a weaker regional crack in the old oceanic lithosphere.
There are a scattering of younger seamounts but those seem more like one off events as opposed to these 7 volcanoes that have been consistently active for a very long time. Thus a hotspot deflected and or altered by the presence of a continent coupled with persistent crustal weak points that help concentrate activity seems to be the best fit of activity.
Also of interest is the referenced paper which looking at hotspot trajectory while accounting for plate motion has not only found that hotspots do move on their own separately from the lithosphere but that these motions appear to preferentially push hotspots towards mid ocean ridges(and or lead to formation of ocean ridges)
With a series of eruptions in several episodes over 10 million years, it should perhaps be viewed as multiple volcanoes which happen to erupt in close proximity but are not otherwise related?
Perhaps so althrough seems to be feed from same shared deep source and inside the same Island edifice so is the same volcano in my opinion
Maybe, but the episodes do share the same summit area. The dikes of the shield stage seem to radiate from either the Valley of Tejeda or the Andén del Toro. The Valley of Tejeda syenite intrusive complex that fed the silicic volcanics is elongated E-W, with one end just next to Andén del Toro, so it is possible it grew from this conduit as a lateral sill system. And then the post-erosional dikes clearly radiate from the Andén del Toro area. So it is a possibility that the whole thing was fed by the same conduit, roughly under the center of the island.
The Canary plume sits below a plate (Africa) that moves much slower than the Pacific plate below Hawaii. Just if we look at the age of Oahu (Honolulu) when it was born 3.9 million years ago, Gran Canaria already was more than 10 million years old! Gran Canaria is like Oahu’s past “Big Island” that would still sit on the plume.
Gran Canaria shows that the Canary hotspot can do tholeiitic basaltic shield volcanoes, and it’s uncertain whether/when/where it will happen again.
How is the behaviour of viscous alkali magmas (Trachyte, Phonolite) compared to Rhyolite? Vesuvius 79 was Phonolite. Does it more sudden eruptions than Rhyolite?
Alkalines are highly Sio2 undersaturated compared to subalkaline melts so have in general much lower viscosity as evolved melts unless they are really cool althrough tracytes are quite viscous, phonolites even less viscosity
Bur their high gas content means there maybe little diffrence If the magmas are very gas rich, phonolites are very so If gas rich
The greatest difference I’m aware of is that phonolites are more fluid than rhyolites (Erebus for example), and when intraplate they might be more prone to form stratovolcanoes due to increased explosivity (Kilimanjaro or Mount Meru are phonolite volcanoes). Another characteristic of phonolites is that they often make spectacular plugs, see Ua Pou in the Marquesas or Pico Cao Grande in the Cameroon Line. Trachytes and rhyolites behave very similar, same as alkali basalt and sub alkaline/tholeiitic basalts are very close in behavior.
Much more fluid Infact as they are in reality not more Sio2 rich than andesites and less polymerisation with alkalinity, but temperatures are also important
But its possible that most Phonolite eruptions are about as fluid as Erebus is, Erebus is fluid enough for some rough pahoehoe probaly caused by past overflowing lava lakes
How sudden did the last Rhyolite plinian eruptions develop? The last significant Rhyolite plinian eruption I remember is Chaitén 2008. It went very quickly from zero to a 21 km high ash plume on first day. But there might have happened unmonitored deformation before.
The Dacite plinian eruptions of St. Helens and Pinatubo had “macro-physical” (for humans sensible without modern equipment) precursory signs in the form of initially phreatic explosions weeks before the main plinian eruption.
Vesuvius 79AD happened suddenly like Chaitén, but with immediate apokalypse for Pompeii. Do we know whether there were any macro-physical precursory signs before?
Vesuvius 79AD was not silicic though, it was highly evolved but SiO2 of phonolite is intermediate composition (it evolves by fractioning other minerals, not necessarily SiO2) and at least from what some of the measured numbers in 1944 are it seems Vesuvius is a very hot volcano. So the eruptions are violent but not viscous. Probably the comparison to an awakening rhyolite volcano is not so appropriate.
I guess it makes sense, alkaline eruptions are probably better described as magma that is made of incompatible elements so dont want to crystalize, the common rule of magma behavior dominated by silica polymerization seems to only apply with tholeiitic or mildly alkaline magmas where SiO2 is more than 40% of the primitive melt, although granted this is probably like 90+% of volcanoes so makes sense. But it even seems to override the increased silica = increased viscosity rule, the most felsic igneous rocks are pegmatites but those are expected to have extremely low viscosity as the amount of other elements concentrated disrupts the formation of a crystal structure, and pegmatites are always found as thin dikes. I dont know if pegmatite has ever been found as an extrusive rock though, even if it was it might have so much gas dissolved it it that it explosively decompresses even deep underground and just makes a maar but with no extrusives. Maybe a small percebtage of maars in old silicic complexes are this, like those craters on the side of Mammoth Mountain that formed in the past millennium, but even that is wild speculation.
If there is a plume! That is an assumption which may not be warranted. The area does not show the traditional sequence of volcanoes. Almost all islands are active and remain so for a very long time. There is some extension westward but that does not coincide with a reduction in activity further east. And this structure is not due to a low velocity of the African plate as there are chains elsewhere around the plate. It looks more like convection currents come from the Atlantic rift, with the upwelling itself far from the Canary Islands
Mantle plume or hotspot seems to be the most fitting still, activity on the eastern end of the chain is much less than in the west, Fuerteventura and Lanzarote may have had recent eruptions, but those are far between and erosion seems to be winning the “race” there as opposed to La Palma or el Hierro.
And there seems to be a clear age progression as well, at least if you take the youngest fossils found in the molten remnants of the sedimentary layer under each island that are incorporated into the magmas and erupted.
El hierro’s fossils are around 1,3 m.a, La Palma’s 3-4 ma.. etc.
Maybe a very low productive plume on a very slow moving plate?
The case against a plume is the long timeline of volcanism here (it dates back 50 million years, perhaps more) and the absence of the bulge that you would expect to form above a plume. Over the long time period, the African plate has also moved quite a bit north but the volcanism does not show this. There is also no anomaly in the lower mantle. One paper calls it a ‘secondary hot spot’, which I think means one without depth. The most recent model I have seen puts as a combination with shallow plume and edge convection along the edge of the crayon, causing intermittent volcanism.
If there is no plume, where does the volcanism come from? The African-European plate boundary is north of Madeira. Maybe the volcanism there is caused by subduction. But the Canary islands are too far away. They sit on a SW line coming from the Atlas mountains.
Your Article about the Atlas earthquake mentions some volcanoes that were active during periods when also the Canary volcanos were active: https://www.volcanocafe.org/the-morocco-marrakesh-earthquake/
The earthcrust below the Canary archipel is thinner than on the Atlas orgency and Africa plate. Maybe there magma sucessfully crosses until the surface that in Morocco more often stays caught kilometers below as deep intrusions. Can we observe intrusions that create plutons below the Atlas (or other orgencies)?
Or could it be heat from under africa seeping round the edge?
I seem to remember that there is a marked elevated temperature anomaly under africa.
The edge of the craton is steep and subject to edge convection. The heat can come from the Atlantic rift or from underneath the continent. The entire northwest coats of Africa has a volcanic line running along it, and has done so for tens of millions of years. The Canary Islands also have this line, but in addition there is a line running into the Atlantic, and that line is hard to fit with edge convection only. I checked at one point whether this line was an extension of the Atlas Mountains but that did not work.
What about a scissoring motion? If plates were to pivot about a point on their mutual border, to one side of the pivot point the boundary would be convergent (pushing up the Atlas mountains, say) and to the other side it would be divergent (allowing magma to bubble up). The rotation could be very slight, leading to only weak rifting on one side and weak folding on the other, but all along one line. The presumed pivot would be offshore of northwest Africa.
I’ve also thought about the intraplate volcanoes of Sahara. Are they mantle plumes? What if the Canary islands are such a mantle plume, but offshore the continent? Maybe the plume itself is a weak one, but is combined with the Atlas volcanic zone. Like Iceland is a combination of Atlantic Rift System with a strong plume.
While there is evidence for a plume it also isn’t a clear cut situation as there seems to be other contributing factors as I posted a few minutes ago base don this paper https://www.sciencedirect.com/science/article/pii/S0012821X2200142X
The activity here seems to have began back in the Maastrichtian and continues into the Holocene even showing a somewhat cyclic renewal cycle where the evolutionary stages of the volcanoes restart potentially as shield stage activity based on the samples which we can observe from rock layers. Even the one of these 7 islands which hasn’t seen Holocene activity seems to lie within the overall rebirth/resurgence period range of 20 to 40 million years so while activity has somewhat trended west we can rule out volcanic eruptions for any of the 7 islands, as opposed to the monogenic activity history that seems to hold for the other minor seamounts.
In this sense when these 7 particular islands erupt the magma it is intruding into old intrusive and volcanic rock layers and thus it should come as no surprise that the eruptive history and eruptive complexity of the Canary islands don’t fit with most hotspot volcanic trends.
Phonolites are the high alkalinity counterpart to andesite in terms of silica levels however as alkaline magmas they tend to have higher temperatures and volatile components than their lower alkalinity counterparts which makes them both somewhat less viscus and somewhat more explosive than their low alkalinity counterparts. The same is likely true for high alkalinity rhyolites.
As for chad’s comment about pegmatites given how their dominant chemical constituent is water, i.e. a pegmatite is a magmatically derived burst of supersaturated water full of ions their crystals appear to be formed during highly turbulent and rapidly evolving intrusion events, i.e. pegmatite crystal formation appears to occur too rapidly for incompatible elements to be forced out of the rapidly precipitating lattice structures even in the case of several meter sized crystals meaning even large crystals often have formed only on timescales of several hours to days. With those characteristics I’m pretty sure any pegmatite intrusion reaching the surface would always be phreatomagmatic unless it was erupting into extremely high pressure deep sea conditions where the water component can remain supercritical.
FWIW, Volcano hotspot has a feature on Hoggar Swell & Co. Does *NOT* mention Canaries but , IIRC, suggests that up-welling from zone re-activated by Africa / Europe collision is offset during rise by root of the NW African craton.
Would this be akin to magma ‘focussed’ by split in subducting plate ? Per several oddities in North America, such as Yellowstone, plus offset ‘anomalous’ centres such as Mt St Helens, Vesuvius and that place on China / Nork border…
https://volcanohotspot.wordpress.com/2023/11/01/recent-volcanic-activity-in-the-hoggar-swell-algeria/#more-28446
Caracedo is by far the best reference on Canarian volcanism. Good choice 👌
Winter in South Scandinavia is a disgrace .. rain and gloomyness and darkness looking like a horror film. So yes woud be good to be in Gran Canaria now sitting on a phonolite plug or a basanite dark sand beach and enjoying some sunny weather
OT: This one is for Jesper.
NASA just posted a picture of their latest fly-by of Io. No major eruption during this visit, but the landscape is scarred by its intense volcanic history.
The full entry with a short description can be found here:
https://apod.nasa.gov/apod/astropix.html
Looks very good but we will have to wait until december and and january for the closer orbits for being able to see more detail.
Lei Kung Fluctus lava flow looks mostly unchanged, Im curious on the other active lava flows that was seen in the Galileo Probe era
Dreams of flying on Juno flying through the.. the immense Aurora in the polar night .. the most powerful magnetic field in the solar system, huge glowing ribbons many Earth diameters long and far below that glow .. Blue flashes can be seen in the darkness.. ligthning flashes from thunderstorms…
The greatest show in the outer solar system togther with Io s volcanoes
Kilauea getting pretty lively, and the monitoring map even has orange (shallow) quakes going much further down the Kamakaia segment of the SWRZ than the end of the connector, and a few more that are south of Kilauea Iki. Still nothing really in the caldera and now another DI has started.
It is looking very likely an eruption will break out in the Kau desert before the end of the year and maybe even before the end of the month at this rate 🙂
Based on elevation too, the upper segment where the 1974 vents are is too high, it is above the lake elevation. However, the area where the connector reaches the Kulanaokuaiki fault and apparently ends is around 900 meters elevation. Kamakaia Hills area is about 750-800 meters elevation.
It didnt erupt in 2021 because the lake was way lower than that back then. I guess it isnt certain, the last eruption also had swarms on the SWRZ and still erupted in the caldera and above the lake nonetheless, but its fast ending is telling that pressure is the drive and not much is released, an eruption either in the caldera or near the outlet would be intense and short lived again, and back to square 1 in a few weeks after once more.
Unless something crazy happens right now we are looking at the first SWRZ eruption in nearly 50 years happening soon 🙂
There should be a new insar on Kilauea in the next few days, it will be very interesting to see the development. SDH is still going up a little bit but slowly, while quakes have been intense along the distal part of the connector. That area is where I think the strongest deformation is.
Kilaueas lavas are superfluid .. some in SWRZ and Mauna Ulu trail are just thin glass sheets covering rocks like at Nyiragongo, it sourely is extremely hot to be able to do that as high temperatures lower the polymerisation alot, have the Halema’uma’u lavas been measured in temperatures ? How hot was the 2008 – 2018 overlook lava lake? these lavas are certainly very fluid .. the only other Thoelitic events thats been same low viscosity in my lifetime is Fagradalshraun 2021 summer
Apparently, it was variable between 1150 and 1300 C 🙂
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9159575/
Thanks!
But I doubt it woud cool that much from the Halema’uma’u chamber and surface, perhaps flaws in the mathematical models so one of these temperatures are probaly correct, and seems unrealistic for it to change in temperatures too
But I not read the paper yet so will do 🙂
For me it looks like the “Middle SWRZ” is most likely to do an eruption. Not the lower strombolian hills that were the excemption inside SWRZ, but also not the high SWRZ eruptions (f.e. 1970s and 1982) with beginning at Summit.
1790 to 1823 most eruptions were at lower altitudes than 1919-1920 (Mauna Iki).
An eruption from the connector wont be like most of the historical observed SWRZ eruptions because they all came from shallow intrusions starting in Halemaumau. 1974 was the only observed connector derived eruption. The Kealaalea and Keaiwa flows also came from the lava in the caldera or upper conduit that would become Halemaumau. The Kamakaia eruptions were from the connector and had strong fountaining as well as the evolved strombolian activity, before becoming a slower pahoehoe eruption.
Eruptions from the connector would begin very fast and with strong fountaining, while a drainout from Halemaumau would be mostly effusive although potentially also very fast depending on elevation. But fundamentally they are different. SWRZ connector eruptions are like ERZ eruptions and begin with gas rich magma that came from the deeper source.
The difficult question is how far the “SWRZ Fires” 1790 to 1823 are a model for future
“SWRZ Fires”. We only have this lonely historical example. That is too little to have certainty for the probable scenarios. If we get a series of Fires, it may be very different to the last one. Volcanoes like to surprise.
Would eruptions from the connector build their own dyke from deeper sources? Then the few green quakes at medium deep levels may be an indicator. There around is possibly a flexible rock layer which allows magma to pass without significant earthquakes and swarms. Single quakes there may be as significant as swarms at other depths. The depth of -15km, where the green quakes occur, is below the marine base of Big Island, but above the mantle. So they may be indicators for feeding the connector.
Interesting that this time the quakes didnt stop with a DI, and a rather big DI too at least compated to the last few.
Maybe when the I part starts, that is when it could get to breaking point.
Would it be incorrect to say that the Canary volcanoes experience two major stages of volcanism? The first is mostly mafic and makes the island, La Palma is in this stage now and probably so is El Heirro although it is not very active presently.
An erosional stage then follows, which is then terminated by the secone wave of volcanism that builds a more evolved edifice. Tenerife is that volcano today. After this is more episodic rare volcanism, which seems to be kond of unrelayed to the original shield and just uses the weak point in the crust, which is what happenes on Lanzarote and probably to some extent all the older islands.
The only weird thing seems to be that the time these transitions take place isnt consistent across the islands. But mafic volcano followed by erosion and then a phonolitic or trachytic volcano in the same place some millions of years later is a common theme and that is very interesting. The first silicic stage of Gran Canaria that was technically part of its stage 1 does seem to be unique though, unless I am mistaken.
Each volcano has a different history, so finding common patterns is difficult.
Lanzarote: The original shield is probably not exposed. A pulse of mostly mafic volcanism around ~15-13 Ma builds a small shield (Los Ajaches), but is possibly just the edge of Fuerteventura’s volcanism. Another pulse of mafic volcanism 7-6 Ma creates a small shield (Famara). In the last 2 Ma, rare but voluminous eruptions built a vast field of long fissures and monogenetic shields.
Fuerteventura: Basal complex starts to form around 30 Ma (possible initial shield phase of Fuerteventura but is very poorly exposed), possibly a N-S rift reaching from the center to the north of the island and maybe even to Lanzarote.. Around 27-26 Ma a nephelinite-carbonatite-phonolite volcano develops in the northern part of the island. From 25 to 20 Ma or so, a series of phonolite, trachyte, nephelinite, and carbonatite complexes develop over the central part of the island (the intrusive core of what may have been a caldera system). Around 20 to 15 Ma voluminous mafic volcanism started in the central part building a shield around the silicic complex, then in the south constructed a new shield, Jandia (16-14 Ma), and finally there is the construction of a shield in the north reaching possibly to Lanzarote (14.5-13.5 Ma). Only minuscule volcanism afterward.
Gran Canaria: Rapid eruption of the mafic lavas 14.6-14 Ma builds the bulk of the volcano. Powerful caldera complex does tens of ignimbrites, a cone sheet swarm, and lava flows, of phonolite, trachyte, and rhyolite 14-10 Ma. Quiet period. Second silicic phase 4.1-3.5 Ma produces the Roque Nublo cycle. Mafic volcanism keeps going to the present.
Tenerife: Main central shield is poorly exposed, oldest lavas 13 Ma in age may have come from a long rift. In the central part of the island 12-9 Ma mafic lavas. Dormancy follows. 6-4 Ma two satellite shields grow to the sides of Tenerife. Since 3.5 Ma the central shield reactivates and produces bimodal volcanism. Phonolite-trachyte explosive and effusive eruptions from the center of the island and mafic eruptions along rifts.
La Gomera: Submarine lavas around 11.5 Ma in age. Main construction may last until 8.5 Ma when volcanism starts to alternate with trachytes-phonolites. 8.5-6.5 Ma a silicic system grows in the center of the island with cone sheet intrusions, may have been a caldera, although no ignimbrites are known to my knowledge. Weakening felsic-mafic volcanism continues until 4 Ma. No activity since.
Fuerteventura is so very eroded and sleepy, many with No knowledge of geology probaly think it as a non volcanic Island, amazingly long lived been active and been there since Oligocene ! thats so long ago that the Canaries where likley competely tropical as the Oligocene was much warmer than today, the landscapes we can barely imagine .. But I imagine green and forested and coral reefs.
Concepcion Bank was likely coeval with Fuerteventura/Lanzarote. They all follow the same rift axis and have around the same starting age.
This paper was interesting but it seems to include Bisabuelas and other seamounts that are far older in the vicinity: https://www.nature.com/articles/srep02107/
Yes, that article is great as it helps us understand the evolution of the area. At least two generations of very small volcanoes came before the Canary Islands.
Concepción is an important volcano that was active around 17.5-16.5 Ma. In my Google Earth data, I have written down the samples as being alkali basalt, which I had forgotten about, so it may have been a powerful volcano. It fills a gap in the Canary Islands history where not much was going on, in between the central mafic activity of Fuerteventura, and the activity of Jandia and Northern Fuerteventura. Fuerteventura and Lanzarote are the subaerial remnants of a chain of several volcanoes, 9 or more systems, that don’t really follow ant age progression. The clear age progression doesn’t kick in until Gran Canaria:
Lanzarote and Furvertuventura sometimes looks like one giant volcano as they are connected coud they share the same magma source?
Well, there is probably some relation. The southern part of Lanzarote is probably part of Fuerteventura’s northern volcano (Tetir), or at least they have the same ages. Lanzarote does have a central shield suggested by gravity data that I don’t think outcrops anywhere though.
I could see some sort of trend here (because calling it a pattern would indicate they are all the same) – shield-building phase (usually mafic), explosive period (primarily felsic), dormancy, and reactivation (starts off felsic for the most part, tapers off to mafic only). It seems to fit the majority of the islands, except for Lanzarote, as per usual, being the black swan, which skips all the felsic parts and dominatingly mafic. (Could be part of Fuerteventura, could not be, who knows.)
A more global topic: Was the last dry (not phreatomagmatic) major plinian eruption Puyehue 2011? It had VEI5
It looks like the “pure” big plinian eruptions don’t occur that often. Since 1980 we’ve had five dry plinians with VEI5 or more. Chaitèn 2008 was a dry plinian eruption but only VEI4 at all.
Depends whether or not you’d class some like Shiveluch as ongoing eruption, it may well have passed the 1km3 mark by now. Fuego is another
Puyehue has been proven to be VEI4. The correct answer is Hudson 1991.
Hudson 1991 was kind of phreatomagmatic too though, erupting through a glacier. It might have been Pinatubo, unless the answer is specifically for VEI 5s in which case it is probably El Chichon. It seems these eruptions are indeed quite uncommon, although there isnt a great deal of difference between a strong VEI 4 and a lower 5, the intensity is similar just longer duration. Maybe it is hard to keep a plinian eruption going long enough to make a VEI 5 without things escalating way beyond that. At least in Kilauea and Bardarbunga it didnt take very much at all to begin a self sustaining collapse, and while those werent explosive many plinian eruptions are mafic or intermediate and dont have viscous magma, the physics at play are likely very similar.
You know, maybe this is actually why it appears as though rhyolite is prone to them, because it takes a lot more than a low 5 to set off a big rhyolitic volcano while a mafic volcano would go caldera. Its a kind of survivor bias in a way…
Nabro?
Beautyful shot showing columnar basalts in Tenerife, sunken below the waves like Atlantis, a Igenous fire monument now sunken under its own anti- itself kind of .. the cool ocean water frozen forever .. the fire vent away
That’s cool.
Interior of a massive Aa lava flow I guess that flowed into the ocean.. souch thick flows cool very slowly, even thinner flows shows signs of jointing, but thicker ones forms souch columns
Tropical and Subtropical seas are so clear and blue and beautyful as well.. contains less nutrients than colder seas further north so less plankton/plant growth and so on, so they are in reality quite meager enviroment for animal life.. but its beautyful, and Hawaii is probaly the clearest and most nutrient starved of any ocean on Earth because of its Isolation, Kailua Kona offshore have a visibility that gets close to destilled water 🙂 visibility of 80 m is possible.
Canaries is also a low nutrients ocean so is very blue too with very good visibility althrough not as good as Hawaii. Most of the worlds population live at the continetal coasts where there is lots of runoff and nutrients influx, so never enjoys clear blue oceans that we finds so alluring. The closest blue waters for most persons in Europe is the Mediterranean Islands , like Sardina, Corsica and Sicily have many incredibley clear spots too.
My own ocean is shit.. dog poop
Just 2 meters visibility offshore green peasoup
I recall crossing the North Sea and for part of the journey, with shallow water and a sandy sea bed, the water was the most amazing emerald colour.
Thats a cold nutrient rich sea so yes will be very green, my own ocean is so fertile ( over fertilized ) thats its a peasoup, poor visibility and lots of productivity.
Hawaii on other hands are pretty much a watery desert, incredibley low in nutrients, warm oceans contains less due to the tropical thermocline, and Hawaiis extreme isolation in the North Pacific Gyre prevents nutrients influx. So Big Island may have the clearest waters in the world, 80 m visibility is possible in some spots offshore and some divers have experienced 450 feet visibility at Molokini Tuff ring 🙂 so Hawaiian waters are superblue indeed
Been in Kona many times .. and gone offshore diving, that clear blue water is stunning they have, something I will never forget, its so very blue its like liquid saphire or deep indigo its stunning
Chad did you saw that too in Big Island? althrough Puna coast with more rainfall is perhaps not as clear
Héctor:
When El Hierro erupted in 2011-2012, one thing that I noticed was the elevation changes of all the Canary Islands in response to something happening with El Hierro. When El Hierro went up, the other islands went down slightly and it seemed almost like they all were floating on some type of balloon like material, say 30-50 km deep. It would be interesting to go back to the GPS records and take a look at the vertical traces.
Thanks, Randall. I’m interested in those things.
Reykjanes area is very active of late. Looks like our favourite intrusion is heaving about. Have Iceland’s Met Office moved their drumplot and seismic charts? All my saved links are going nowhere.
Getting quite dense too now, so signs it maybe magmatic involment, coud be an intrusion, but we needs to wait, this is not directly under the fagradalsfjall, but woud not be supprising If it is magma as its probaly the case. Looks like its close to the blue lagoon… that maybe becomming the Red Lagoon soon
Its basically right under the Blue Lagoon. Its probably not a dike as the intensity of the eruptions at this location probably requires fast intrusion. But that can change and may well be a wrong assumption to begin with.
But this is definitely very interesting, just because Fagradalsfjall is the only volcano to erupt so far doesnt mean it is the only one that is active.
Is it where there have been previous intrusions?
Close near Thorbjörn was a sill in 2020 I think
It would be a shame from an economy perspective to lose the blue lagoon.
I’d like to think it’s closed for today at least but can’t seem to find anything indicating! Another M4.5 right underneath Thorbjorn 40 minutes ago.
I mean, unless this eruption floods Grindavik or the airport highway, it seems that having eruptions so close and accessible has been a boom for tourism. I remember something like half a million people saw eruption 1, which is equivalent to everyone in the country and asking half of them to bring someone else. Even if lower than that it is still in the hundreds of thousands.
And the lagoon is a byproduct of a geothermal station which will absolutely be either rebuilt or replaced if destroyed, so not necessarily the end anyway.
There’s this one:
http://skjalfti-tremor.com/tremor-fagradalsfjall.html
I think their server is misconfigured and makes your browser believe it should use https instead of http, but then the server responds with a 404. With chrome on android it seems like it’s no longer possible to manually edit the url to remove the s. Your experience might vary between browsers.
The plots are still there if you manage to make the browser request http instead of https.
Yes, I found out that I can no longer edit the s out of https on my Chrome browser. However, my Edge browser accepts the URL without the s. This is on a Windows PC.
Also Bardarbunga and Grimsfjall have had some quakes. A long time that the “Volcano Family” of Vatnajökull has been dormant now! Didn’t Carl predict Grimsvötn to erupt some years ago?
Clive, as alternative you can use
https://vafri.is/quake/#close
When you click on a circle, info appears.
Click on the linked Seismomter or GPs to view drumplots etc.
Like this
https://www.livescience.com/planet-earth/volcanos/perilous-expedition-to-uninhabited-island-in-south-atlantic-confirms-existence-of-worlds-8th-lava-lake
No pictures yet but apparently the lava lake long suspected at Mt Michael in the South Sandwich islands, has been observed for the first time and confirmed.
Interesting that these islands were named as the southern counterpart to the Sandwich islands, which we now know as Hawaii 🙂
Hopes they post photos soon the lava lake is saied to be very large and very active
Info from IMO on current quakes swarm on Reykjanes peninsula. A little vague.
https://en.vedur.is/about-imo/news/a-seismic-swarm-started-north-of-grindavik-last-night
today`s update on the ongoing unrest is now available: https://en.vedur.is/about-imo/news/a-seismic-swarm-started-north-of-grindavik-last-night
“New satellite data has not arrived yet
30.10.2023
Updated 30th of October at 11:30am
The Sentinel satellite data expected to be received yesterday has not arrived yet, however the cGPS data in the area around Svartensgi and Þorbjörn show that the deformation is still ongoing. The deformation rate since the beginning of this intrusive event has been slightly decreasing over time. Preliminary deformation model results suggest the average depth, where the magmatic instrusion is occurring, is about 4 km.
Over the past 24 hours about 1300 earthquakes have been automatically detected on the Reykjanes Peninsula. Most of this seismicity is located at a depth between 2-4 km. The largest earthquake had a magnitude M2.7 on the 29 October at 11:40UTC.
Scientists from the Icelandic Meteorological Office are undertaking additional surface measurements in the area, including geochemical observations. Regular communication is maintained between IMO, HS-Orka and the Civil Protection while this unrest continues.”
The swarm returned strongly today, but at Fagradalsfjall, not Grindavik. I think we are heading for Fag IV.
I cant see anything at Fagradalsfjall Albert, all of the quakes are further west, part of Svartsengi. Newest spot is next to Sylingarfell, which is one of the hills next to Blue Lagoon although the swarm at present is on the car side from the lagoon.
Yes, it is in between the blue lagoon and Fagradalsfjall, not at the latter.
earthquake_time_depth_week.png
Interesting, the earthquakes at Pahala and similar depth seem to have a small escalation at the same time as the last two DI events on Kilauea, which also lead to decrease of the shallow swarm. But the last DI, which was a lot bigger, apparently barely made a dent…
The I part has started too, and its one of those hard starts, the ‘V’ shape as HVO calls it. I wonder if it is the final straw and an eruption will begin in the next couple days, its getting really intense now and most of these swarms dont last longer than a month.
🙂
Insar of Kilauea for the past two weeks. Seems inflation is indeed focussed at the far end of the connector, compared to the previous interval that is below.
Magma is really filling up that rift. If only some sort of instrument measured the area in question, its a bit of an unknown what is going on which is a weird thing to say about Kilauea.
http://www.mounts-project.com/static/data_mounts/kilauea10/2023/kilauea10_20231012T161646_20231024T161646_VV_ifg.png
When it exceeds the overlying rock pressure it will be fireworks show, will also be fun to see the superfluid lavas thats typical of that area on Kilauea, thin sheets. Looks like a lava flood like 1974 is on the horizon I guess
Kilaueas lavas are so very fluid they can leave thin veneers on rocks and the ground and the rest of the lava flow simply drains away, this was also seen around the vent at Fagradalshraun in 2021 s ”silver phase” Mauna Ulu and 1974 have alot of these features as well as many SWRZ flows like the great crack. Have any viscosity estimates done near these hawaii flows ?
Hopes its able to flow into caldera so we can get some ”fire falls” If it erupts close to it, its probaly will be the caldera next time, after all this is related to the caldera magma system that sits a little south of the caldera itself.
Quakes on Rejykanes seem to have moved toward the east of the highway – there is some sort of old 100m edifice nearby east of the Blue Lagoon, in the adjacent valley to Fagra. Most are still around the 5km depth mark though.
12 M3.0+ events in the past 13 hours so it’s fairly energetic.
Impressive, probably magmatic though it doesn’t look like a dike. Likely it’s magma accumulation, it will snap at some point,t but as usual the final rupture is hard to predict.
Might anyone know the link for the Iceland Met Office tremor and drum charts? All my regular links broke and I assume they’ve moved, or been taken off?
Thanks
I explained this a bit up in the comments. You need to drop the s in https and use http instead, but it seems like some chrome update won’t let you do that anymore. For me it doesn’t work on android, but still works on windows, but since I have no control over the updates (it-department pushes them out), that will probably change soon.
In the chrome settings, under “Privacy and security”, there’s a checkbox for “Always use secure connections”, the default in your browser has probably recently changed. If you turn that off you should be able to access http sites, even when the https site is responding. It’s a problem in this case because the https looks misconfigured on the server. That said it’s a setting that should really always be on.
Thank you!
Clive. Someone put up this link yesterday. Hope it works for you.
http://skjalfti-tremor.com/tremor-fagradalsfjall.html
Thank you!
There is definitely inflation at the MANE station, which is at the top of the Hilina Pali and about 5 km east of the end of the connector. The quakes are getting stronger too and more of them are starting to appear further down the SWRZ,like they are marking the zone of weakness. It even looks like there is a bit of a cluster at the Kamakaia hills.
To me this is the final bit of info that says the next eruption will be on the SWRZ. This never happened before the other eruptions and it is low enough that a summit eruption cant relieve tge pressure now.
There is definite inflation there. however, do note it is only about 1 cm while near Kilauea over the same period it is 20cm. MANE is on the edge of the bulge, not anywhere near the centre. The bulge is where the insar is.
I was more referring to the eastward movement, it looks small but eastward at this location is not out to sea and the connector is at least a few km away, it is closer to the surface vertically than it is to MANE. So all of that 2 cm eastwards is pressure pushing the rock not flank sliding. The vertical is not really resolved enough to give a number but it us clear the points plot upwards more now than any other time. The fact the station is picking up any signal at all in this way is what is significant.
I have seen the newest insar, the inflation that was so extremely clear right at the southern edge of the caldera 2 weeks ago is not really visible now while an area to the south is mostly off the image but is clearly where the action is now. The earthquakes are also now more powerful and numerous in the more distal area of the connector too, which is in agreement with the movement of nearby instruments. I tried to link both the new insar and the one from 2 weeks ago above but it didnt display the image in the comment.
22 October
28 October
Definite increase in seismicity at the lower end.
Anak Krakatau and Hunga Tonga’s Greek cousin:
Mystery of volcanic tsunami solved after 373 years (Phys.org, 26 Oct)
Interesting article. The eruption appears to’ve left a 2.5 km breached caldera, and the breach caused the tsunami.
Pretty big eruption apparently that I’ve never heard of! Found one article that says its dense rock equivalent was 2km^3. https://www.nature.com/articles/s41598-020-71991-y The current crater has a negative volume of close to 1km^3, based on the average rim height. So a nice friendly VEI 5 in the Mediterranean.
While Mexico had its surprise category-5 hurricane out of nowhere, the same happened on the other side of the ocean where Vanuatu was hit earlier this week by a category-5 cyclone a month before the start of the cyclone season.
Poor Ambrym the lower Island there
The northern island was hit much harder. Acapulco was also devastated. And still some people in power argue that climate change is not their problem. Living in denial does not change the reality. This is just the beginning.
You cannot blame climate change for a single storm!
How many storms do you need?
How many storms do you need?
More than one or two. You were talking about one storm only there or at a stretch about two with Vanuatu and Mexico. That’s weather.
Is there evidence for climate change? Yes. Can you legitimately claim what you claimed? No. You conflated weather with climate. A classic many do on both sides when the weather favours their hobby horse.
An equivalent would be claiming type 3 supernovae are common based on the single one confirmed up until now.
Hurricanes actually appear to be one of the least reliable methods of tracking climate change. Numbers haven’t changed. ACE has altered a bit but not much. Far more reliable are average temperature records. They definitely do show a distinct change.
The Acapulco storm was extreme in rate of intensification and in the location for a storm of this strength. The Vanuatu storm was well outside the season for such storms. Sure, you can blame the current El Niño, but we have had El Niños before and much stronger ones. Remember the huge storms in the Caribbean in the past years, or the large ones hitting Florida. The number of tropical storms has only increased a bit but their peak strength has gone up. Our memory is not very good at recognising how different the new normal is. Be prepared for more of this. This year is extreme in many ways, with exceptionally warm weather worldwide and climate records broken by unheard off margins. Several things contribute, and next year may well be a bit cooler again. But in a few years this kind of weather will be normal. I see that the first action of the new speaker in the US is to go against funding to limit climate change. With that attitude, you’d better expect worse than this.
If we have a pattern of storms like Hurricane Otis then yes that is climate change. From what I recall there is indeed such a pattern starting to become evident. However Hurricane Otis y itself cannot be cited as evidence of climate change.
Please dont tell me you are a climate change denier mjf 🙁
A single storm has multiple factors. Climate change is a longterm factor. El Nino a midterm factor. Weather/meteorological conditions are a shortterm factor (which can be very complicated).
Well, I’m unsure if it’s climate change, El Nino, Hunga Tonga, or the ship fuel thing, but here in Spain it has been somewhat crazy weather since late May. Around late May weather became very unstable and there would be thunderstorms happening on a nearly daily basis in some parts of Spain. June to early July produced unseasonal amounts of rain in what is usually a dry month, in places 3 or 4 times more than the average. A series of supercell outbreaks of increasing intensity started happening in June, sometimes on consecutive days. This culminated in the outbreak of July 6 where a high-precipitation supercell hit Zargoza producing historic flooding and unbelievable images of places I know very well. At the same time, another supercell thunderstorm produced a likely tornado (something you don’t see every year in the Spanish interior) in the small town of Albalate del Arzobispo, as well as chicken-egg-sized hail, and precipitation rates of 30 mm in 10 minutes measured in a nearby town. From then, the weather was mostly stable until September. On September 3 a cutoff low was expected to produce rainfall of well over 100 mm, mostly in a few hours, in the Spanish capital of Madrid. The models changed their mind in the last moment and predicted what eventually happened, which was the worst of the cutoff low hitting to the west of Madrid where there was catastrophic flooding, so that the capital was not as affected as it was initially expected. On October 19 a very active cold front broke rain records in several places. Madrid had 114 mm of rain in a single day which was the highest recorded in that station since at least 1860. More recently, on October 22, a subtropical storm landed in the south of Spain where winds of over 100 km/h sustained for more than 15 minutes threw down more than 10 % of the trees in the city of Huelva, in what is said to have been an unprecedented event.
This is true. Maggi was indeed right.
Nothing very significant has been done though, because pressure group/political interference from all sides hijack this real and existential problem to further their own agendas, which results in ineffectual real results. We need to massively increase wind and solar energy production and triple our grid capacity as THE most urgent measures. When we get near to 100% renewable energy production we should introduce electric cars whilst continuing to expand solar/wind to provide the extra power required. We are nowhere near 100% renewable electricity outside a few small countries.
Air travel should be pretty well banned and consideration should be made to bringing homes and workplaces together to reduce commuting.
etc etc. Instead we go off half-cock, promoting electric cars before we have spare renewable power to run them, fighting every new pylon, solar farm and wind turbine proposal that is made and refusing to give uo medium and long haul travel.
PS My solar has kept me off grid since June, although I will soon have to tap into grid power. Heating and car excluded (mostly).
Even if you run an EV on a generator with brand new batteries it is carbon neutral after a couple years, the smaller the battery or the more distance driven the shorter the neutrality point is reached. You can never reach that point in a fossil powered car.
And more importantly their emissions, whatever they are, are not generated in close proximity to the population, the tailpipe emissions are a huge health hazard EVs dont have. It is easier to control emissions if they are made in 1 place that doesnt move than thousands of moving sources subject to human error.
I disagree, and have posted the maths before.
I haver seen your maths and it is at odds with the maths of tens of thousands of automotive and other engineers Farmeroz. I respect that you are a smart person who backs up their claims with evidence but odds like that are not in your favor.
And it doesnt address the elephant in the room, no combustion engine, even run on hydrogen, is going to solve the problem of tailpipe emissions when the oxidant is an atmosphere that contains nitrogen. But EVs dont, there is a reason forklifts with engines are illegal to run in areas without adequate ventilation, but apparently it is ok for you to drive thousands of those engines past pedestrians every day…
Farmeroz is actively reducing his carbon footprint, so I think you are actually on the same side in this argument! There is no dispute on what needs doing. The question is how to achieve it. Neither of you deny the problem so that is a good start. And car pollution is indeed a major and largely unrecognised killer. In London, it has only recently been diagnosed as a cause of death. Not all of that is from the engine: part is from the tyres. In the UK, we have the strange situation that cars are bing moved from diesel to electric, but trains are being changed the other way, mainly because planned electrification of the lines (decades overdue) has now even canceled. Different departments, I guess; there is clearly no risk of a coherent government policy. Electric cars are ideal for city use but not there yet for long distance travel. I am not sure what your argument about hydrogen refers to. It produces water? Hydrogen is a niche product though, not only because of how it is made (at the moment it generates more greenhouse emissions than the fuel it replaces) but also because of a relatively low end-to-end efficiency. Its use is mainly as an energy storage.
In general, efficiency is on part with electrification in its importance. Renewables do not get generate as much as fossil fuels: their use depends on us using less. Which should be fine as there is a lot of room for improvement. Whenever we buy a new appliance, our goal is to get something a lot more efficient than the previous one. But for our new car, we could not afford the hybrid one so went for one that was only somewhat better than our old one but with the aim to replace it again in 2 years or so.
I only contest the opinion on EVs not anything else, as you say we are I wish I had my own energy source, although in Tasmania all of our energy grid is over 100% renewable anyway (net exporter) so it may not be a necessary desire. It certainly is in some other parts of Australia though. I dont actually worry about Africa and more remote parts of Asia, they get to start from scratch and most are going renewable. I also dont worry bout china, they are just after energy of all kinds, their renewable percentage is actually very high. I worry about the US most of all actually…
My point on hydrogen was that it is still being combusted in an ICE, it is the high temperature that causes the secondary reaction between N2 and O2 to make NOx. There are also other very good reasons why H2 is a poor choice of fuel, it has low volumetric energy density which would make a H2 ICE car probably have a range of under 100 km, it is very expensive, and fuel cells are extremely expensive and have questionable reliability in real world conditions. Toyota really screwed up persuing it, they were early investors in Tesla and could have been where they are now. But we absolutely need to invest in making green H2 on a huge scale for the Haber process so the research is not useless, just misguided.
At least in a train, the diesel engine is only used as a generator unless you guys are going into some really archaic stuff. Diesel electric is significantly better fuel economy, the engines can run at high load at optimum RPM, getting efficiency of nearly 50% and be tuned to capture emissions with optimum air flow. You cant do that in a car with its variable RPM, those engines only average about 30% efficiency. It may be less efficient to convert the power to electricity as opposed to mechanical gears but the difference is slight, and the electric motors are much lighter and much more powerful than the gearbox too, as well as eliminating about 90% of the maintenence. But still sad to see it is because of poor funding this must happen.
Regarding your car, I would just keep your existing car and then get an EV, skip the hybrid stage. I have a corolla hybrid and it is a fantastic ICE car but a sht electric car, it is about as much an electric car as a turbocharger is a kind of jet engine. It still requires you to go get petrol, maybe a little less often but still, and is considered an ICE car as you cant plug it in, despite what Toyota likes to claim as them being ‘self charging’ electric cars… The only good thing is the punchy instant torque, it is way faster than the normal corolla despite the specs, and it actually weighs less too. but it is certainly not an EV.
Used model 3s on the Tesla website go for 24,000 pounds if you dont mid them being a few years old, but EV maintenece schedule is basically just changing tyres and wiper fluid so they are almost brand new at that age. There might be cheaper options elsewhere too, although long range EVs that arent Teslas are a rare sight before the covid era, so not old enough yet I guess.
Being honest, when I had a polestar 2 rental in New Zealand, I actually stopped longer than the charging time, my range anxiety was for a wifi signal at the destination to let me actually use the charger not their availability… 🙂 it only takes an hour if you actually want to charge it completely to 100%, as the charging speed drops off hard after 90%. The 60 kWh pack in a P2 or a model 3 will charge in minutes at a fast charger that can do more than 100 kW, which are nearly ubiquitous.
I just long for the day when the obnoxious trumpet of ICE engines is not a constant background hum. The air quality in the covid years was noted for being way better, no one was driving around. Not to mention the fact it will make energy security a million times easier, you can put a solar panel or wind turbine almost anywhere.
Not to mention that it is very hard to contain H2. It’s even worse than natural gas for leaking as if everything, however seemingly solid, is a sieve. It’s quite inefficient to use unless it’s produced right at the site of use, right before use. Also, it’s extremely flammable and prone to exploding, as the passengers and crew of the Hindenberg discovered the hard way.
As for fuel cells, they should improve. Your own body runs on fuel cells, after a fashion, though they don’t use H2 as fuel but rather a short-chain organic molecule called pyruvate, after some enzymes cleave glucose and a few other simple sugars into pairs of pyruvate molecules. A viable fuel cell vehicle might be possible based on, say, propane, and would be carbon neutral if the source of the propane was (e.g. biofuels). We have existing supply chains and methods for moving propane around and storing it without too many leaks (or explosions) or too much loss. It’s a lot less troublesome than hydrogen. I would expect, though, that EVs will prove superior to FCVs in most or all applications, whatever the latter’s fuels.
The best way to store hydrogen is as CH4, which is methane. However we apparently arent very good at stopping that leaking so at a cost of some volume it is probably better to store it in either methanol or ammonia.
I should say, the sorts of fuel cells that work at lower temperatures like those in the Toyota Mirai are expensive and not especially efficient, as well as needing purified H2 and dry air. Solid oxide fuel cells are very robust and dont necessarily need to contain platinum. The downside is they require very high temperature over 500 C and closer to 1000 C is better. But an advantage to this is they can directly run on any hydrogen containing fuel without a secondary step, as well as electrochemically react carbon, it is basically a petrol battery, the most efficient way to turn hydrocarbons into electricity. Their efficiency approaches 70% in real world tests although that is at a large scale. It is unlikely this tech will ever be sensible for primary power to a vehicle as tgey are very slow to start and have low power density but as a potential range extender that also provides a heat source it may work. Although I expect battery technology will allow EVs to have much longer range than ICE vehicles on average before 2030, SOFCs probably have much greater potential for shipping and possibly very long distance aircraft.
I am exited for whoever cracks rechargable metal air batteries. Only 5% of a Li-ion is actually Li… most of the weight is in the transition metal oxide the cathode is made of. And despite that a base level model 3 can go 500 km on a charge now and weigh less than 2 tons with a full crew of passengers. Imagine if the cells were 10% Li, or 20, or 50 🙂 you could probably drive that thing further while towing a trailer than any ICE car will ever go in perfect conditions.
Cat 5 on the Australian scale but Cat 4 on the Saffir-Simpson.
Humans needs to emitt less cO2 and yes cO2 have never rised this fast since complex life began, really skyrocketing it is since late modern Industrial age began. Only Chicxulub limestone impact did something similar prevuoisly I think.
The problem is that most persons simply cannot understand that concept and never will without better school public education, and they misstakes the current extreme rise in antropogenic cO2 as a natural cause like other previous natural cO2 variations, when todays rise is not natural at all. They often blame volcanoes ..but that wont work either as volcanism been quite sluggish since end of Cretaceous as seafloor spreading slowed down in the non pacific parts. Todays extreme rise in cO2 is defentivly human caused and started with the Rise of industrial revolution and specialy the second one
It will be very intresting to see how much human cO2 will really be needed to kill off the migthy Northen continetal winter high pressures, that are still extremely cold today in winter in Canada and Asia for example. In earlier natural greenhouses these areas had tropical rainforest climates like at PETM but that was also extreme examples.
The climate is indeed warming and it will be very intresting to see how much human cO2 is needed to turn example Germany into a subtropical climate, winters in South Scandinavia and South Iceland does have gotten very mild in the last 60 years with most of the snow cover gone, but most of Scandinavia its northen and middle parts still have very Severe Winters almost like Canada. The large continetal interiors have gotten warmer summers but still haves incredibley cold Winters. We humans are lucky that we started polluting a Cold Earth with low cO2 .. rather than that cO2 was higher when industrial revolution began .. maybe we have some time to change
Will be fun to how much cO2 is needed to kill the winters in northen and central parts of Scandinavia. These winters are still very strong today even with 450 PPM, during earlier natural hothouse we have had tropical climates at almost the same latitudes. But that maybe requiring 2000 PPM, and we will never reach that due to investment and development of batteries and electricity transports
But Winters was much colder in Europe before the modern age and rise in cO2 remebers from 1600 s paintings that UK had very cold winters and South Sweden had polar winters almost perhaps because cO2 was pre – Industrial back then.
The climate warming still takes a while, the atmosphere has only had over 400 ppm CO2 for less than a decade it will take quite a lot more decades to equilibrate. Most of Antarctica was melted in the Pliocene at 400 ppm too, but it will probably take over 1000 years to melt the ice sitting in East Antarctica that is mostly above sea level. The west side though, that is a big unknown, if the ocean ever gets under it then the whole thing can lift up and float, probably breaking up and being exposed to the world ocean. It would still take decades, maybe even a few centuries, but it would enormously accelerate sea level rise. Although this is not a likely scenario still at least not probably before 2100.
Basically the poles and ocean are massive heat sinks that are absorbing all the heat, once those are filled, well, things are going to change and rather dramatically…
Yes the wast icesheet at Antartica and the cold ocean around is probaly slowing things alot haves a strong cooling effect.
But In South Scandinavia it have been some noticable effects during the last 60 years, its moving away from the cold frigid winters thats typical of the Scandinavian interior, to a snow free oceanic winter. But rest of Scandinavia is still quite cold in winter, Northen Sweden and Finland are frozen
Once the heat sink is filled perhaps Europe woud quickly turn back to the Miocene climate with Mediterranean becomming more humid and nearly tropical, and central and west Europe becomming like the Subtropical China today, I see that easly happen as Europe is already almost humid subtropical in the West Europe at example france coast
The 3d earthquake plot for iceland still works. Its interesting to look at.
https://skjalftar.is/3d/
There was an M4 earlier today.
I get the 3D grid displayed at my tablet screen but somehow the quakes do not appear.
It might be another Chrome issue. When I open it in the Samsung browser, everthing is visible!
if you see the numbers at the top of the screen and tap them it filters by magnitude. I accidentally clicked the 4 and it didn’t display any earthquakes.
Confirmed 2,0 and 2,7 quakes closer to surface N/NNW of Grindavik at Reykjanes today?
https://en.vedur.is/earthquakes-and-volcanism/earthquakes/reykjanesridge/#view=table
Friday 27.10.2023 04:03:22 63.862 -22.451 0.4 km 2.7 99.0 2.6 km N of Grindavík
Friday 27.10.2023 04:06:50 63.865 -22.456 0.1 km 2.0 99.0 2.9 km NNW of Grindavík
Seems there is an overall change in depht for 2+ eq’s since yesterday afternoon…?
326 quakes in 24 hours on the peninsula.
I think the dyke is still in the same system as before but an eruption in the adjacent valley would be interesting. They may have to build some form of barrier to protect the road/Blue Lagoon.
This is definitely volcanic in origin, as there earthquakes are not releasing the tension but are continuing. In the previous episodes it could take a couple of these swarms over months to get going. It will be interesting to see whether this time, one swarm is enough. Probably not, I expect.
It’s interesting that they are occurring strong only on the west side of Fagrasdfjall. Very little on the east side. Is this because of the angle of the plates in Reykjanes, the bookshelf faulting, the dyke coming up diagonally? Or is Krysuvik system just very ductile in comparison?
It is where the activity in early 2020 was located. It moved to Fagradalsfjall in 2021 where it erupted. There had however been earlier activity in Fagradalsfjall, a couple of years before. It seems the two locations are quite closely linked.
IMO are saying these are triggered earthquakes, ie a local fault system moving to accommodate magma accumulation. Other faults have moved since the onset of this volcano-tectonic episode in late 2019.
Source: https://en.vedur.is/about-imo/news/a-seismic-swarm-started-north-of-grindavik-last-night
They’ve observed inflation (land uplift) near Festarfjall (Party Mountain): https://en.vedur.is/about-imo/news/a-seismic-swarm-started-north-of-grindavik-last-night
“These measurements could indicate the presence of magma at depth along the continuation of north-east – south-west-trending dyke intrusions, which have formed under Fagradalsfjall since 2021.” Festarfjall station is close to the southern coast road. They interprete the inflation as Magma accumulation at 10km depth. “The seismic activity is interpreted as the response of the crust to the stress changes induced by continued magmatic inflow at depth beneath the Fagradalsfjall volcanic system.”:
Does the extension at Fagradalsfjall by Magma accumulation cause tectonic stress to the east and west? Then we could both the earthquakes around Grindavik and Kleifarvatn view as impact by Fagradalsfjall’s extension. It is like a temporary graben/divergent zone.
Magma accumulation would increase tension all around it. We’ve seen triggered quakes to the north, south and east of the intrusions earlier. Don’t know enough about the local geology to comment on the order in which local faults respond.
Forgot to mention that we have seen triggered quakes to the west earlier too. There has also been some indication of a magma intrusion at Mt Þorbjörn a while back.
Maybe we see the creation of a magma chamber below possible dykes. The shield volcano wasn’t active since 8000 years ago. It could need to build a new magma chamber again that can support future sustained shield eruptions.
Think there is inflation north of Grindavik now, if I am reading the GPS plots correctly.
Don’t know if it is a new magma intrusion there or still a response to the intrusion at Fagradalsfjall.
Guess we will have to wait for the InSAR pictures when something can be detected.
It looks like a combination of a possible intrusion on the top and fault movement at the left. This was the same shape as when the last intrusion happened but that was not a dike so seems unlikely this is either. The eruptions never follow the fault in the preserved examples, even if maybe magma does move along it deeper down at the surface it seems to get out in other ways.
All of the recent inflation both before and after the last eruption has been at Fagradalsfjall too, even deep down, would be strange to suddenly get a shallowish intrusion outside that area. I have seen something about it maybe being caused by magma movement at the south end of the Fagradalsfjall area near the coast but nothing official on that still. If there are quakes though then pressure exists somewhere.
The 2022 and (first? 🙂 )2023 eruptions seem to have involved magma that was in the crust and maybe sat there from the first eruption, not being directly fed by mantle decompression. Maybe after a few years the next eruption could be different.
IMO confirm the uplift; it is centred near the Blue Lagoon.
https://en.vedur.is/about-imo/news/a-seismic-swarm-started-north-of-grindavik-last-night
Uplift isnt the same as dike though, there isnt that sort of butterfly pattern of a dike but it is definitely some sort if magma accumulation
The map says “magma accumulation at 10km depth”. That’s below typical intrusions. Maybe something happening in the deep crust close to Moho. Fagradalsfjall may show us how a typical shield volcano is born. It was active 8000 years ago, it died and is like Phoenix getting alive again. I don’t think that a magma chamber would have survived 8000 years. It must have become Gabbro.
The creation of a new magma chamber may look like an intrusion, but deeper and broader.
https://www.usgs.gov/observatories/yvo/news/lotta-lava-new-insights-timing-yellowstones-most-recent-rhyolite-eruptions
I’m pretty sure those age groups represent individual fissure eruptions which is something hinted at in the article too. So then, a 130 km3 DRE lava flow would be a relatively normal eruption for a caldera of this scale. That no other volcano does anything even close to this speaks volumes of how unique the system is.
Amazing dwarfs the chao lava flow yes yellowstone is a monster in terms of capacity of large eruptions, whole steaming mountain plateaus are souch large ryholitic flows when they erupt 🙂 130 km3 are also much bigger than previous estimates of yellowstone obsidian flows that puts them only a few times larger than Laki
The Yellowstone system definitely is a crazy place for sure. It is particularly interesting that no other supervolcano, even the absolute mosters like Toba, have been able to erupt something liek this though. I guess Toba has the excuse of it being not that long, but still you would expect to see massive rhyolite flows in the Andes but the only examples exist at what will probably become supervolcanoes and not ones that have already graduated.
Seems very good evidence all on its own that Yellowstone is far from dead, if anything it might be one of the volcanoes that has the highest rate of magma flow anywhere on earth to keep so much magma molten, just that unlike in Hawaii it is able to leave the system without erupting.
The other options is that its gigantic hydrothermal system is able to act as a large enough heat sink to effectively make it an open conduit as far as heat is concerned. Some of the hydrothermal explosions that have hppened since the last glaciation were comparable to VEI 5s or even 6s, yet involved no actions of magma at all. The heat flux of Yellowstone is about 6.3 gigawatts across the caldera, apparently 30x higher than average. The geothermal flux of Grimsvotn across its caldera is supposedly 1.2 gigawatts, although its caldera is around 100x smaller. But Grimsvotn is also very active and maybe more importantly its caldera is probably very young and maybe only 240 years old. Maybe because it doenst have a large hydrothermal system I wasnt able to find numbers for Kilauea, but to keep a water lake at 80 C obviously requires a lot… But again, it also erupts constantly, not sitting dormant for 70 millennia.
I wonder if maybe (this is a huge speculation) the magma that does go into Yellowstone partly escapes towards the Snake River plain, it would make some sense given that is a worn path with extensive magma alteration and presumably still a lot of active magma at depth anyway with how many volcanoes are there and their rather absurd size and intensity of eruption compared to most monogenetic cones in North America. The composition is different, but that may not be a deal breaker necessarily.
Damn, only 0.01 shy of what it’d take to erupt backward in time! 🙂
Well, that is over 35 km2. A Delorean is about 8 m2 in area. So the flux is only about 275 watts over the area of a Delorean. So you could probably run the lights and maybe get some free heating but you would need to focus all of that heat into one tiny spot to make it time travel.
I expect though, that certain parts of the caldera, like the cliff at the southern edge, are probably where most of that number comes from, maybe you could get a bit closer 🙂
I do wonder how Yellowstone will be effected as it is just starting to march into the craton proper. Cratons are deep. That combined with thinner underside in its wake from the heat may tend to encourage backward flow. I wonder if it skips a beat at some point. Goes way sideways for a while until gets too far forward and has to punch a new hole.
True Cratonic volcanism involves Phonolites kimberlites and Melilitites really super strange magmas, true cratonic volcanism is indeed very rare and often needs some kind of fault to exploit. Finland had a huge Phonolite volcano a few 100 million years ago, probaly will be more alkaline as the litosphere gets deeper in the future there. The magma source is powerful but hard to say if it will be able to handle the cratonic behemoth, the speed of the plate moving over it also plays a role, how long its allowed to heat a certain spot of the litosphere
I have to wonder this myself though given the seismic tomography shown during Nick Zentner’s A to Z Baja BC livestream series last fall/winter it can be somewhat argued that Craton deformation/break up has already begun with the Colorado plateau getting broken off of the Craton proper. Of course its not just Yellowstone since Yellowstone appears to be centered on a junction within the mantle discontinuity that connects to the Juan de Fuca Ridge and East Pacific Rise. In that sense there is a pile up of subducted slab walls and the craton proper which the hotspot has to melt its way through at it kind of looks like its in the midst of melting through the slab wall curtain beneath the craton though its hard to say for sure with Seismic tomography.
I know the Snake river plain’s lavas and magmas have been linked directly to the Yellowstone hotspot on the basis of igneous petrology so that does seem to be the current focus of magmatic activity relative to the plume that is to the east though the recent onset of volcanism to the eastern edge of the Colorado plateau could have something to do with Yellowstone based on its relative proximity in the same sort of way as what is happening with the Snake river plain. Has anyone done a detailed trace element melt source igneous petrology analysis of the eruptive products of Dotsero? I suspect not given that the volcanic system there appears to be relatively understudied in that Geology Hub was able to find an older cinder cone vent hiding in plain sight but perhaps I’ll be pleasantly surprised my brief search found some studies but they were focused more on the general rock types rather than trying to identify the source melt trace element signature.
On another more speculative note I can’t help but suspect that the respective strains from the general clockwise rotation of western North America centered around Yellowstone and the Adirondack uplift dome/hotspot may be the source of strain that are reactivating old fault zones in the Craton such as the New Madrid seismic zone and the adjacent Wabash Valley Seismic Zone. At least if you recognize the extended Yellowstone Rio Grande boundary for clockwise rotation these faults are roughly midway between these two zones of cratonic deformation though generally positioned to the south relative to the hotspots themselves. How much tension can get transferred internally within a craton? As the reactivation of old rift scars seems the kind of faults one might expect to respond to building strain. I doubt it is simple since cratons are old and complicated and they are relatively far away but I suspect there is a significant indirect contribution to old fault systems taking away strain. I wonder if some of those more northerly old rift scars related to the great lakes might one day get reactivated so long as the hotspots are allowed to do their thing uninterrupted. Has any studies been done on craton responses to strain?
Finally HVO woke up: Current Volcano Watch article talks about SWRZ unrest: https://www.usgs.gov/observatories/hvo/news/volcano-watch-unrest-continues-kilauea-summit
The “observations indicate that magma is accumulating in the geologically complex south caldera region. […] Intrusions also occurred here in the 1960s, 1970s, early 1980s, and in 2006. But only one, in December 1974, led to an eruption.”
They see three scenarios:
1. No eruption
2. Summit eruption inside the caldera
3. Summit eruption outside the caldera, to the south or southwest
They don’t mention the SWRZ. Are they right or wrong to only expect something in the summit region?
Well, an eruption to the south or southwest of the caldera is an eruption in the SWRZ… We might very well get a Kamakaia Hills eruption next, and then this article will be incorrect because of their fixation of speaking about the summit. But yes, a Halema’uma’u eruption is always an option. Another option is a non-eruptive dike, an important option from a volcanological perspective that is different from nothing happening.
They don’t use the term SWRZ for this area. It seems that is used only for the more distant parts of the rift
It seems so. Names should be used when useful though. The dikes that erupt in the distal parts of the SWRZ often originate from the area where the inflation and earthquakes are happening, although they can also come from Halema’uma’u. And the earthquakes are lighting up what is pretty much the vertebral axis of the SWRZ.
Do they fear to cause panic if they mention SWRZ? I sometimes have had the impression that HVO warns conservative/cautious, like it prefers to be officially surprised by a volcanic eruption than to warn too much before.
Probably more the fact it is an eruption that isnt inside the caldera, if they say rift zone people will think of 2018, even though no one lives on any part of the SWRZ.
The terminology they use is also rather vague, HVO got quite a lot of criticism when Mauna Loa erupted because of their terminology around the fissures that opened on the southwest side of Mokuaweoweo. Those fissures were not on the line of the SWRZ, but if the eruption had focussed there lava would have still gone down to the Kona coast regardless which would have been rather a bad look.
I guess, most people think of a summit eruption at either volcano as an eruption inside the calderas, anything else outside is potentially a hazard. HVO uses a more general zone of elevation it seems like, for Mauna Loa it is anything over and at Kilauea it seems to ve anything within the outermost caldera fault. Although, the present activity was outside of the caldera fault from the start anyway, they consider 1974 as a SWRZ eruption, and the distal tip is almost as far from Halemaumau as Pu’u O’o is so I dont know…
Basically, HVO does seem to be avoiding calling this a rift zone event. Its very confusing, anyone who knows anything about Kilauea can see this quake swarm is way outside the caldera, it gives off an impression they probably dont intend.
Mauna Loa 2022 was in the first hours very unpredictable. It may have resulted in a SWRZ lava flood towards inhabited areas. Mauna Loa doesn’t erupt that often, so a “false warning” there would be more acceptable. It doesn’t happen inflationary.
The risk of Mauna Loa’s SWRZ may cause people to expect something similar if they hear of Kilauea’s SWRZ. We don’t should expect that they all know the difference. This could be a reason that HVO doesn’t mention Kilauea’s SWRZ. But they should use the chance and time they still have to brief the population about the typical behaviour of Kilauea’s SWRZ: Low rate, even if duration is long.
I think people in Hawaii pretty well understand that Kilauea and Mauna Loa are separate, they have hazard zones that are based around land insurance, the hazard zones of both volcanoes are quite far apart. I think people know that the Kau desert and Pahala area is not related to Mauna Loa, although a Mauna Loa eruption could send lava flowing into Pahala if it lasted long enough, but that is different.
I think it really is just the simple fact that HVO is hesitant to predict an eruption outside of the caldera so soon after 2018. That was only 5 years ago, their predictions (if you can call them that, nothing was said with certainty) were that an eruption outside the caldera would probably not happen for at least a decade, and probably not before 2030. But the speed at which the caldera has filled up I think has surprised them. The fact that a part of the volcano that has only erupted once in living memory and 50 years ago is also looking to be the next center of activity is not helping…
“Every ‘failed eruption’ is a successful intrusion!”
That is assuming Kilauea actually really even does truely non-eruptive intrusions to relieve pressure. From what I can see whenever it appears to do so the area rapidly becomes vigorously eruptive. In 1961 there was a large intrusion in the middle ERZ, with a few tiny eruptions, but the area became flooded over with lava by 1969, when Mauna Ulu started. And in 1975 magma pushed into the ERZ to cause the major earthquake of that year, and Pu’u O’o formed exactly behind the part of the flank that moved.
Supposedly 1924 failed to erupt but the ocean is deep even very close to the cape, 500 meters 5 km offshore. A flow was found by ROV in the 90s that was too hot to be over 100 years old, at 3 km depth.
It is possible the next event will be a SWRZ intrusion, that may not erupt lava to the surface. But I am going to bet the new rift will be where most eruptions happen for years thereafter.
The August 1981 SWRZ dike event was one of the largest deflations of Kilauea and that area hasn’t erupted since 1974. But there are plenty of examples, the 2007 Father’s Day dike intrusion, or all the Koae Fault System dikes.
More was referring to how in most cases places on Kilauea that ave large intrusions tend to start erupting a lot. I imagine if Pu’u O’o had not opened then the SWRZ might have had a chance, although I guess it never got that.
2007 dike did erupt, very small but it counts 🙂
Are there still old dykes like of 1981 that contain old/evolved magma?
Maybe a little, but probably not enough to be relevant to an eruption. The 1981 dike also started from a different bit of the connector than the Kamakaia hills eruptions probably started from. I guess we will probably find out how this area works pretty soon though.
The most recent GPS measurements suggest that at the moment the activity is centred at the AHUP location.
The 1960s, 70s, 80s, 2000s, were also before 2018 and when the ERZ was a key location of activity. The eruption in 1974 was not long after Mauna Ulu, which had reached a summit elevation equal to the floor of Halemaumau, and which had for 5 years acted as a sort of barrier to magma moving further down the ERZ as it was doing during the 60s. So basically the easiest option was to go out of the SWRZ connector. Not long after and magma probably forced its way into the ERZ again in the quake of 1975 although evidently not at a depth shallow enough to result in an immediate eruption. That quake probably did have a big part in why Pu’u O’o could stay open for so long though.
Nowdays the ERZ is completely cut off, there seems to be some quakes on a short part of its connector but this is also on the outer caldera fault so probably not much. Not when compared to the cloud of quakes just to the west anyway…
There has also been quite a big change in the number of quakes on the more distal part of the connector which has occurred after the map in the article. I put it further up in another comment chain but the difference over only 6 days is quite clear and does give the impression something is going to break soon. There is a good chance of a non-eruptive intrusion, but only if it goes a long way down, there is still only going to be a couple hours at most between the first opening of the dike and an eruption starting if it does happen I expect.
Since 2019 we had a lot of deep swarm quakes near Pahala. We don’t know if the magma which came up since 2019 has extruded in Halema’uma’u’s eruption or is rather going to erupt in SWRZ. Is is possible that magma has found a way from Pahala directly to SWRZ or would it first pass through a central system? It is not far away horizontally, only vertically very far.
Some GPS stations on Kilauea show heavy deformation since August, more than before the last eruption in September:
MANE station (east of Mauna Iki) has recently moved much towards south and east. All in all it looks like an accelerating development. More than before the last eruption of September 10-16.
Hey can someone explain to me the mechanics of the seismic activity in Reykjanes at the moment? I note that that the scientists said the earthquakes near Grindavik are not due to magma intrusion there but rather pressure release due to accumulation underneath neighbouring areas.
But how is it that pressure has resulted in 4000+ earthquakes in that one area while other areas seem to have very little? Sorry I’m only an amateur so don’t really understand these things.
And I don’t believe it’s just because the Blue Lagoon is built on the hardest rock in the world 🙂
That is a very good question. In the end, all earthquakes are due to rock fracturing, whether tectonic or induced by magma. Something is applying pressure. In the case of tectonics, it is the slow movement of the plates and faults, and the friction along the fault which keeps them locked in place. At some point the force exceeds the friction and things suddenly begin to move. This may cause more force nearby so that another part of the fault gives way, but in general the follow-up quakes will be smaller than the main one. The size of the earthquake comes from the length of the fault and the amount of friction: the weaker the lock (for instance, when someone injected water into it), the more frequent but smaller are the earthquakes. When the pressure comes from magma, the addition of liquid rock nearby increases the pressure on the rock. This causes failure, but because the increase happened rather fast you get many earthquakes of comparable size. Still, after a while it calms down. But it can resume if magma keep accumulating and rebuilds the stress. The other thing that can happen is that the magma itself moves. It finds weaknesses, either horizontal (sill) or vertical (dike). This movement has to break the rock and this gives a near-continuous sequence of earthquakes. In the current case, it seems to be an existing fault that is giving way under the enhanced pressure. It is possible magma will move into this fault but the magma may not be there. If the magma is indeed underneath fagradalsfjall, it will be looking for an exit there and at some point one would expect earthquake swarms in that area. Some inflation near Grindavik does not necessarily mean that the magma is there: that can also be the movement of the fault.
Thank you for the reply, that’s very interesting. So to summarise:
-the intense seismic swarm is likely due to the pressure of nearby magma resulting in a fault giving way, somewhere in the area indicated, north of Grindavik (?)
-the swarm may calm down unless further magma related pressure is applied
-there remains an unknown factor of whether magma is accumulating there (in addition to Fagradalsfjall) and also how connected the areas are
Hope I have captured the meaning correctly!
This is a great explanation of what is going on, answers my questions perfectly. I guess in time it will be revealed whether or not there is magma going into to adjacent Svartsengi system or if it is all Fagra. I know previous volcanic episodes in this stretch have had a sort of domino effect and have each went off in turn, although the current area of eruption didn’t go off during the volcanic period 1000 years ago while those around it did. https://icelandmonitor.mbl.is/news/news/2021/03/05/could_volcanic_period_be_ahead/
Now there are new developments. IMO reports uplift detected west of mount Þorbjörn. It’s visible in InSAR and GPS data. To me it seems like the initial sequence, which looked like bookshelf faulting progressing from west to east, created an opportunity for magma to enter the crust. The last strong cluster of quakes jumped back to the location where the sequence started and those quakes were shallower than the first ones.
At about the same time as that last shallow cluster the first signs of uplift is visible in the GPS data. This could spell bad news for Grindavík. Let’s hope not.
Won’t do much for the Blue Lagoon or the power station either. Who get’s power from there?
All of the Reykjanes peninsula gets power from the power plant as well as hot water.
So that includes the airport and Reykjavik?
No, not Reykjavik…but the airport
Without a moment tensor available for reference, it’s possible the uplift is due to oblique faulting?
Not sure about that. I must admit I’m a bit confused by the InSAR image. It doesn’t say anything about what has been done in the processing, whether it’s line of sight changes or isolated vertical component. It doesn’t indicate direction to the satellite.
Here’s the thing: the GPS at Festarfjall shows uplift, but the InSAR picture shows subsidence in that area. That makes me suspect that we’re looking at phase unwrapped LOS changes, which includes horizontal deformation. That makes it a bit hard to determine what in the red area is uplift and what is horizontal motion.
GPS stations around mount Þorbjörn do indicate an inflation centered just west of Þorbjörn. The text from IMO says new InSAR measurements are expected today. Let’s see what they show.
We’ve seen west of Þorbjörn uplift events before so I think we should assume this swarm is the same thing happening again. For a third time, I think?
Fifth inflation event, according to IMO (update 28/10/2023)
https://en.vedur.is/about-imo/news/a-seismic-swarm-started-north-of-grindavik-last-night
It is likely that Þorbjörn/Reykjanes and Fagradalsfjall are “communicating systems” with some kind of interaction between both. Fagradalsfjall expands with accumulation of magma. This expansion causes earthquakes and tectonic stress to the east and west. At the same time also Reykjanes is slowly awakening and to rise magma. This is influenced by Fagradalsfjall’s expansion, but can have a reverse effect on Fagradalsfjall’s magmatic system. At the Moho level there may also happen some interaction we can’t observe empirically.
Think there is a link to Krýsuvík, too. The swarms are preceded by seismic activity near Krýsuvík.
No idea whether the link is volcanic or tectonic.
That’s not entirely true Albert – “earthquakes are due to rock fracturing” – especially in volcanic/hydrothermal areas.
It’s important to consider non double couple events, in particular deviatoric solutions involving significant CLVD – most especially where fluid movements may be involved. This point is seen in its most extreme case in an underground nuclear test, where no rock slides past another, rather *everything* moves *out* – a pure volumetric change, but one that can register as an earthquake of significant magnitude.
During the recent Taupō unrest, the mainshock (unlike pretty much all the other events in the sequence) exhibited exactly this kind of behaviour – a mechanism related to volumetric change rather than simply and only rock fracturing. In fact, I’m a co-author on a paper on this sequence that’s currently with Seismica for review. I’ll post a link if and when it survives review!
Just for clarification what are/is CLVD? Thanks
An earthquake normally involves movement in a certain direction, for instance along a fault. That is a ‘double couple. The alternative is a ‘compensated linear vector dipole or CLVD’ where the motions average out and there is no one direction
When we talk about different earthquake mechanisms we refer to the associated moment tensor. What the moment tensor is is explained here:
https://mxrap.com/2019/07/26/moment-tensors-a-practical-guide/
An explosion will indeed register as an earthquake. I guess phreatomagmatic eruptions are of that type, and I should have listed that. In those ‘non double couples’ where rock moves outwarss, I think the actual earthquake is still related to rock fracturing during the expansion, is’t it? On the other hand, where magma moves out you get caldera collapses (Kilauea 2018, Bardarbunga 2014) and those are just falling rock, so that is the type you mention. I hope we can look forward to a post on your paper, when it appears!
Prior to the Holuhraun eruption, there were theories about the CVLD quakes at Bárðarbunga that they were caused by a rapid magma exchange between two vertically stacked magma chambers. If these are modeled as two pure volumetric sources, with a net zero volumetric change for the entire system, you do end up with a CLVD solution for the combined effect.
I think this theory was proven wrong by the Holuhraun eruption, where individual quakes with identical CLVD solutions (only reversed) were linked to vertical drops in the overlying ice sheet, thus linking it directly to motion on the ring fault.
According to Volcanodiscovery Etna has done some mild Strombolian explosions. They can be an early prelude for a paroxysm. Then we get an example of alkali Basaltic volcanism like Gran Canaria once did.
Another update today:
https://en.vedur.is/about-imo/news/a-seismic-swarm-started-north-of-grindavik-last-night
About the Svartsengi swarm/inflation. What we have is an inflating balloon sort of to speak (probably more like a systems of sills but I’m keeping it simple), the balloon inflates until it bursts, There is a higher risk when Svartsengi is inflating that it will snap and erupt. Svartsengi eruptions are nothing like Fagradalsfjall. Fagradalsfjall is slow, it has subglacial and postglacial shield volcanoes, and it’s fissure eruptions have been very nice and slow. Svartsengi is fast lava floods, more violent than Fagradalsfajall, and the dike probably grows much faster too. I have talked about some of the eruptions here:
https://www.volcanocafe.org/the-reykjanes-fires/
So this is somewhat of a risky situation. It’s not overly dangerous, most likely not life-threatening, but it’s not your harmless Fagradalsfall eruption either.
Depends how close it is to Grindavik, I suppose. If it is where the swarm is now then there will be some time, although depending on the volume and topography possibly not a lot. If it erupts right outside or in the town though then…
There would also occur some risk for phreatic or phreatomagmatic explosions. The Blue Lagoon shows that water is there moving below the surface, so magma can hit it and explode.
Yes and no. Most of the water is pumped into the bedrock and is already superheated below the surface. The returning water and vapor is used in the powerplant. Most of the water (if not all) in the Blue lagoon is the clean “garbage” water from the powerplant.
Would they already observe anything if magma comes 1km close to the surface?
Thank you for providing the information. I note that when uplift is mentioned, it generally is talked about in very short timescales, x number of cm in x number of days (for example 3cm in 2 days I think for the current Svartsengi mini episode was mentioned last week.) But based on the articles, the Svartsengi/Reykjanes system has been warming up and generating uplift for several years now, any idea of the total uplift in the area across all these events? Surely that would give us an idea of the magma present, or has the magma run away after failing to find a new home on the surface of the land? 🙂
It hasn’t been going on for that many years. I think the first uplift was detected in 2020. Before that it was subsiding.
Here’s a really good map resource when it comes to Icland’s geology:
https://arcgisserver.isor.is/?lon=-20.25047&lat=64.11371&zoom=7&layers%5B%5D=satellite&layers%5B%5D=verticalVelocities
In this link a map layer is enabled that shows vertical changes between 2015 and 2018. We have uplift around Vatnajökull, mainly because of reduced ice load and melting of the glacier. Note that during the same period there was subsidence at Askja, Torfajökull and Reykjanes. All these spots now show land rise instead.
There are now quakes starting to happen 5-10 km underneath Kilaueas caldera, but still nothing at all at shallow depth within its boundary. There also looks to be a cluster of small quakes right at the Kamakaia hills but I dont know how accurately these small quakes are located.
I do remember though that the intermediate depth quakes under the caldera only started happening about a week before the last eruption, so I think we are getting very close now.
Deformation of the Caldera also becomes more even now. It looks as if positive deformation happens at SWRZ, while the Caldera receives less magma than in September.
If we look back at May 2018 when the eruption migrated from the Summit towards Leilani Estates, was it a similar situation like now? Can we learn a bit from 2018 for the current developmend at SWRZ?
All in all we may view the summit eruptions 2020 to 9/2023 as “Summit Fires” which now may end like the 2008-2018 lava lake in Halema’uma’u ended in the first days of May 2018.
Small earthquake series under La Gomera since yesterday, probably nothing volcano related, but the first time I see La Gomera “moving”
Yes I noticed this too, looks mostly like a north to south trending line.
I suspect people have already answered this multiple times but I always wondered how that volcano became “extinct” when it’s surrounded by the youngest volcanoes in the Canary Islands.
https://www.livescience.com/animals/land-mammals/22000-foot-volcano-summit-is-home-to-earths-highest-dwelling-vertebrates-study-confirms
Very impressive at 22 000 feet volcano summit
HVO finally released a map and some data about the last eruption on Kilauea.
The eruption was very intense, over 18 million m3 of lava in just 5 days, even more than I had expected earlier. And yet the volcano had reached a point of pressurzation only 3 weeks later. That would imply a supply rate of nearly 1 million m3 daily which may well be continuing.
There is also confirmation of the elevation of the vents. The vents at the base of the east wall are at 3200 ft elevation, or 975 meters. The major cones are between 3000 and 3100, or 914-944 meters , but that was before they grew and their size was considerable by the end, I would be surprised if they werent well over the 950 mark when it stopped. The lava lake at the laser range finder is 411 meters deep, starting from 517 meters elevation, so the lake at that spot is at 927 meters.
The southernmost part of the swarm on the SWRZ, adjacent to Kulanaokuaiki pali, is also below the elevation of the lava surface in Halemaumau now too, for the first time since any eruption after 2018 that this can be said with certainty. If this area is where dikes start towards the kamakaia hills, which are about 200 meters lower still, then gravity is in favor of a rift eruption, and this might be the most important factor of all. I have said it now a lot of times 🙂 but all of the evidence is adding up.
So the lava lake is so heavy now that it supresses eruptions in the caldera itself by its own weight, insanely dense too being degassed fluid lava
Which makes me wonder if Kilauea’s height will ever increase appreciably. Maybe not until Kamaʻehuakanaloa takes over from Mauna Loa and Kilauea Junior starts to form, thereby pinching off Kilauea’s ERZ.
IMO:
Monday
30.10.2023 12:19:25 63.987 -19.828 12.7 km 3.8 90.01 7.8 km W of Hekla
Just tectonics
Just a ghost quake. A false detection caused by the shaking from Reykjanes. Pro tip: if the quality is less than 99, go to the drumplots and look for a matching waveform. In this case it’s easy to see that it’s from the big quake at Reykjanes. It looks like two quakes – that’s P-wave and S-wave arrivals. It’s also a bit smeared out. Local quakes are sharp.
New post is up! A Kipuka guest post on the impact of one of the Reykjanes fire eruptions of a thousand years ago.
https://www.volcanocafe.org/volcanism-and-the-christianization-of-iceland/