Snow is beautiful. It turns the world white and unblemished. Children love it for play, grown-ups love it for what it hides. Soon the snow will melt again, or worse, it will age like the world ages, lose its colour and become pockmarked with dirt. The beauty is temporary, here today, gone tomorrow. What was hidden will be revealed again – a memory come back to life, for better or worse.
Glaciers lack the beauty of snow. They carry the scars of age, the collected debris of the years. The surface can be so dirty that it looks like rubble, and needs a fall of snow to beautify. You need to dig down to find the ice. There may also be black layers embedded in the ice, evidence of nearby volcanic eruptions. Vatnajokul is full of those, caused by the frequent eruptions of Grimsvotn. But like the snow, the glacier hides what lies below. At the bottom is the rock, made barren by the scouring of the ice. Once the ice melts (as it will, one day), the scraped rock surfaces. It can take a long time before new soil builds up. We can still see the aftermath of the ice age in the scoured, soil-less lands of northern Canada, the west coast of Sweden, and many other places.
The rock which lies hidden below the ice contains the memory of a landscape that predates the glacier. There are events here from long ago. And not all that it covers is expected. This is the story of one such event, hidden below the ice of Greenland.
Inglefield Land
The Nares Strait separates the northwest coast of Greenland from Ellesmere Island. According to political ownership, Europe and Canada are only 30 km apart here. Geology, of course, puts both sides of the divide on the American plate. The straight line of the Nares Strait is typical for a fault line, an old one as there are no earthquakes here now. Indeed, this once was a strike-slip fault with some 70 km offset. The width suggests that there may also have been some extension. The fault was active around the opening of the Labrador Sea to the south, 60 million years ago. The precise date is not known, though.
Along the Nares Strait are some ice-free areas of land. The largest of these is Inglefield Land. It is 10 degrees north of the arctic circle, and the climate is not kind. There are only three months each year where the average temperature is above freezing, and in winter -20C is normal. The US has an airbase nearby, at Thule. It was the cold war at its coldest. Still, in sheltered places there is grass and other tundra vegetation.
There are people for whom this is home. High in the arctic, the area has a small population of Inughuit, polar Inuit who have been here for centuries. About 800 live in the region around Thule.
http://tiinaitkonen.com/works/inughuit-1995-2002/
Archeologists have uncovered some of their ancient dwellings. The people here lived in houses for the nine months of winter, mainly in the area around Marshal Bay. (There is not enough snow for igloos.) The houses were partly dug into the ground, with an entrance tunnel, a stone-paved floor, walls made from cobbles and a roof build from stone and sod. In the summer the people would remove the roof to let the house dry out, and move away to do summerly things (hunting along the coast and in the eastern part of Inglefield Land), before returning in autumn to reassemble the dwelling. The dwellings that were investigated all had the roof removed: the people had left in spring as normal, clearly expecting to return in autumn but this time had not done so. Whether they had not returned or had build a new house nearby is not known. Archaeology cannot answer all questions: it only finds what was left, not what was taken.
Source: Darwent et al. 2007, Arctic Anthropology
In the 1860’s a few Inuit migrated north from Baffin Island and mixed with the local population. They re-introduced some forgotten technologies, such as bow-and-arrow, and kayaks. Westerners too came and they developed the Thule trading station, which later became the airbase.
The Inughuit were thus not the last to live here. Neither were they the first. The Inughuit had arrived in the area around 1300 AD (the people of that era are known as the Thule.) Before them came the Dorset people, seal and walrus hunters who lived here from 2000 BC to around 1100 AD. The longest Late Dorset longhouse known in Greenland was discovered in the Inglefield area, dating from before 1000 AD. Genetic studies have shown that the Inughuit are not their descendants. As an interesting aside, the Dorset people used iron blades on their harpoons, with the iron taken from the Cape York iron meteorite, found on the ice a little to the south. Stone tools were used to hack off iron fragments from the large meteorite. By about 1300 AD, the local Thule obtained some trade good from the Vikings to the south, perhaps traded during the summer walrus hunt. Different worlds mingled here.
Inglefield Mobile Belt
Sentinel image, August 2021
Inglefield Land lies north of Thule. It is an ice-free coastal region, a 20-km wide arctic desert with little precipitation – no more than 150 mm per year. In-land lies the Greenland ice sheet which spills over the mountains into large glaciers. The Hiawatha glacier which lies above Inglefield Land does not reach the coast (unlike the Humboldt glacier to its north), leaving Inglefield Land habitable for non-vegetarians. The area has been ice free since 6000 BC, when the ice barrier in the Nares Strait collapsed and warmer water from the south entered the Strait. After 1500 AD the ice began to advance again as the Little Ice Age took hold, and areas in Greenland further north than Inglefield became abandoned. Nowadays, as almost everywhere on Earth, the ice is retreating again, but the Hiawatha glacier remains larger than it was 2000 years ago.
The sparse vegetation grows on ancient rock. The bedrock at Inglefield Land is just under 2 billion years ago. It is an interesting region for its geology. In geology too, this was a place where worlds collided. We now recognize an east-west structure extending from here across Ellesmere Island. It is called the Inglefield Mobile Belt. The belt lines up with the edge of the old craton of Northern Canada, all the way to Alaska. Is this all part of the same structure, the old fault where North America and Siberia once came together and separated again? We have written about this in the White Christmas post: the time when the world almost ended. Later, the oldest parts of Alaska migrated 2000 km along this fault, to the west where it rotated into its present location (see the Wrangellia post). We don’t know for certain whether this is all the same structure. Sometimes alignments are real, and sometimes they are just coincidences.
Magnetic map showing the east-west linear belt. Source: Nutman et al 2011. https://ro.uow.edu.au/scipapers/910/
The rocks here are far older than the Franklin event of White Christmas. The rock to the north has an age of 2.5 billion years. There was a later event which intruded magma and granite, dated to 1.9 billion years ago. This was apparently a plate collision which tilted layers vertically. A volcanic island arc may have been involved, coming in from the south. Behind it followed a continental block that is around 2.8 billion years old which now forms the area around Baffin Bay. The two blocks came together in the Inglefield Mobile Belt, with the old volcanic arc contributing to the southern part. The southern craton is now called the Rae craton. The Inglefield Mobile Belt is a young suture, in comparison, a 1.9-billion-year interloper still keeping the two oldies apart.
Geological map of Inglefield Land Source https://www.mdpi.com/2072-4292/11/20/2430
After the parts had come together, Inglefield had a fairly uneventful life. During the Cambrian it sank below sea level, and sediment covered the old rock. At some time a short fault formed in the northern part, running southwest to northeast. It runs parallel to the Nanes Straits and may have formed at the same time, an ‘also-ran’ fault that eventually failed. It is recognized because hydrothermal activity left a gold/copper mix on the surface.
Hiawatha glacier
The Hiawatha glacier lies east of the northern section of Inglefield Land, close to this gold-copper belt, and rises above it. It forms a semi-circular shape, attached to the Greenland ice sheet further in-land; a thin lobe of ice extends from Hiawatha to the northwest, flowing through an opening in the rock wall into a valley. The photo below shows the snow-covered ancient bed rock, with the thin lobe of ice and in the background the arc of the large glacier rising above it all. In the summer, pools of melt water develop on the far side of the Hiawatha glacier.
NASA image, taken from wikimedia
The Hiawatha glacier never attracted much attention. Ice is not scarce in Greenland, and the area was of no particular importance. Science looked elsewhere.
Impact
The first direct evidence that the glacier was well worth a closer look came during a visit in July 2016. A few hundred meters beyond the end point of the Hiawatha glacier lies a sandy flood plain, where a river deposits sediment from below the glacier. This floodplain had started to form after 2010, in response to the rapid local warming. During the one-day visit, sand was collected from the floodplain for analysis. The team found crystals of shocked quartz among the sand. Such crystals form in highly energetic events. A large impact seemed the most likely explanation, and the implication was that somewhere under the Hiawatha glacier there was an impact crater. It was time to remove the ice.
Crystals found in the search. ‘A’ shows the linear shock features. They run at several angles: this is sometimes seen in the central uplift of large impact craters. ‘G’ is an ellipsoidal grain with seems to have shrunk a bit: this is typical for a melt droplet, ejected by an explosion.
Of course, removing the ice is not trivial (though it is not beyond our technology – pumping CO2 into the atmosphere will eventually do the trick). To look below the ice, there are two faster options. One way is to drill through it. That requires luck, as the drilling only samples one location and that may miss the expected crater. The other is to use radar. Perhaps surprising, a radar signal at a frequency of tens of MHz (wavelengths of 10-20 meters) can penetrate ice. Not perfectly: imperfections in the ice will scatter some of the radar signal. Especially layers of volcanic ash can be problematic. This makes the method perhaps less suitable for Iceland, where glaciers are full of these layers, but Greenland has had no volcanic activity for the last tens of millions of years. The little Icelandic or Alaskan ash is too little to interfere with the radar. Internal boundaries in the ice also reflect the radar signal. This may for instance be at a boundary between stationary and flowing ice. A shear zone with broken ice will give lots of reflections.
The strongest boundary is at the bottom of the ice sheet, where the ice lies on what remains of the bedrock, after 3 million years of scraping. If enough of the radar signal makes it through to the bottom, a nice reflection signal tells you the depth of the ice. Tests have shown that such a radar can see through 3 kilometers of ice. Put the radar on an airplane and fly it across the entire ice sheet, and the radar will produce a map of the real, deeply buried surface of Greenland. The job is perfect for NASA which owns several research planes, used for various purposes. The mapping has been done over the past decades. The instrumentation has improved over that time. It now uses an ultra-wide band system developed in Kansas; it transmits 6 kW of power using 8 antennas, covers a frequency range of 150-600 MHz, and emits pulses that repeat at a frequency of 10 kHz. The transmitter is on the body of the plane; two of the three receivers are mounted on the wings. (The third receiver is the transmitter.) The aircraft flies 350 meters above the ice. The radar can measure the depth with an accuracy of better than 20 m.
Here is an example of such a radar profile, taken somewhere in Greenland. It shows the different layers where the ice has internal reflections, the chaos of a shear zone, and very clearly the grounding layer. The empty regions in the left part are cause by strong reflections higher up, leaving too little signal to get through. On the right there is another empty region; it is caused by a steep cliff on the bottom which reflects the radar signal away from the receiving aircraft.
The search for the shocked crystals had of course not been done on a hunch. It was still a closely guarded secret, but the radar mapping done over decades had shown signs of something extraordinary. A few months earlier, a more detailed radar survey of the Hiawatha glacier had confirmed the signs. The team had chartered the helicopter for a day to confirm what they already suspected. There were only 18 hours to find the confirmation, but that was enough.
There was indeed a meteor crater underneath the Hiawatha glacier, and it was not a small one. Neither was it a typical large, 10-km crater. It wasn’t large: it was huge. It turned out, the Hiawatha glacier was the crater. The semicircular shape of the glacier was caused by the crater rim. The glacier had grown inside a huge impact crater, filled it to the brim and grown up further. The glacier extended only about 1 kilometer outside of the crater – that single kilometer had hidden the secret. This was among the 25 largest impact craters known on Earth, measuring a tremendous 31 kilometers across. And no one knew.
The crater rim turned out to be 320 meter high, with a further 600 meter of ice thickness above this at the highest point of the Hiawatha glacier.
The bottom of the crater was rather flat, with a 50-meter tall rise in the central 8 kilometer. This shape is typical for such a large crater. Small craters (such as Meteor Crater in the US) have a bowl shape, with the deepest point at the centre. This what you get from an explosion in solid rock. Volcanic craters, if not filled with lava, have the same shape. But explosions in soft rock create a flat surface inside the crater. This is seen for instance in maars, where the explosion happens in wet rock. The explosion originally makes the same bowl shape, but the soft rock flows back and reshapes the bowl into a plate. Big impacts do this because they have so much energy that they partially melt the rock below. A very large impact can even cut through the crust, and expose the ductile layers below.
Gosse impact crater, Australia. This crater is 5 km across and has some similarity to Hiawatha, although much smaller. It is too small to show a central peak.
Why the central rise? It is known from large craters on the moon: they often have a central peak. It comes from rebound. The explosion pushes down the rock below, and after the explosion the rock rebounds and overshoots, finally freezing into position as a central mountain. (In an even larger impact, the rebounded mountain collapses again before it freezes, and in a second rebound forms a ring around the centre.) In Hiawatha, the central peak has been largely removed by erosion from the ice, and remains as a low plateau.
The crater rim is breached in two places. One is on the southeastern side, where two channels have merged. The second is on the northwest, is much smaller and is the source of the small lobe of ice flowing into the valley. Apart from this, the structure is remarkably well preserved. This may be because the bedrock in Greenland is so hard and so resistant to erosion (all erodable material has long gone). It might also be because the structure is young.
The impact happened within the Inglefield Mobile Belt. We know that the belt extends to Hiawatha: the sediment carried by the river from the northwestern glacier has the same composition as the material from the belt. The crater is symmetric and shows no deformation that would have happened during the formation of the belt. Therefore, it formed after the Mobile Belt had become immobile. This however is not a severe constraint. Very little deformation has happened here since. Even the opening of the Nares Strait might not have affected the area of the crater.
However, the crater is not as deep as it must have been originally: when it formed, it would have been 800 meters deep. That suggests that the rim and central peak have been significantly eroded. Erosion rates for Greenland are not well known: it could have taken anywhere from 50,000 to 50 million years.
Dating the crater is hard enough. Can we date the ice? Ideally, that would be done by extracting an ice core and counting the annual layers. The desert-like climate ensures that the annual layers are thin. At 10 cm precipitation per year, a kilometer of ice can build up in 10,000 years. In reality the layers will be much thinner than the annual precipitation rate, because of evaporation and compression. Thus, the ice could be as old as the ice age.
About 100 meters above the bed rock, the radar mapping shows a layer which reflects a lot of the radar signal. This has been seen elsewhere in Greenland. Where it reaches the surface, it has been shown to date to the Younger Dryas, the sudden cold and dry period when the ice age briefly came back, 13,000 years ago. The layer contains a lot of debris. If the layer inside Hiawatha is the same it means that the ice here is at least as old as the start of the holocene. Below this layer, the structure of the ice is complex. Ice from the late glacial period, (more than 20,000 years ago) which is present in the Greenland ice sheet, is not seen or is strongly deformed inside Hiawatha.
Surprisingly, the radar reflections show evidence for ground water underneath the glacier. This may be the source of the sediment in the river. Could the ground water come from the residual heat of the impact? That heat could linger for up to 100,000 years. However, this is speculative.
Based on the evidence from the crater and the ice, the original discoverers argued for a date within the past few million years (the pleistocene). This implies a highish erosion rate to bring the rim down by 500 meters.
The Younger Dryas
Could the crater be much younger than this? The crater lacks ice from the ice age. This has led to the suggestion that the crater did not exist during the ice age: it formed in the warmer period between the end of the ice age and the onset of the Younger Dryas. This was an extraordinary claim. Impacts of this size (requiring an impactor of 1.5-2 km across) may occur on Earth perhaps once every few million years. To have one only barely 10,000 years old would be a major event.
There had been other, earlier suggestions that a major impact had happened somewhere on Earth around this time. The original claim came from spherules and melt-glass found on sites in Pennsylvania and several other places. The sites had been dated to the start of the Younger Dryas. These locations also show enhanced iridium and platinum, as might come from a major impact. It quickly developed into a catastrophe theory, with the impact being the cause of the extinction of the large mammals in North America, the disappearance of the Clovis culture, and even the Younger Dryas itself. Enhanced iridium and platinum was also reported from a few sites in the southern hemisphere. Evidence for widespread forest burning in North America added to the evidence for the disruption. But a culprit had not been found: there was no impact crater of the right age and size.
The theory ran into trouble when later analysis showed that several of the original sites did not date to the Younger Dryas. A statistical analysis of the carbon dates from the sites confirmed that the various sites did not trace the same time. To get around the lack of a crater, the suggestion had been made that instead of a single event, it had been a meteor swarm with airbursts across the globe. To explain the variety of dates, a cometary swarm was proposed with impacts over a period of time. When a theory needs such complexities to explain missing evidence, it begins to look rather weak. What it needed was an actual crater. Could Hiawatha be that crater? It was in the right location for North America, and such an age would neatly explain the missing late glacial ice inside Hiawatha.
A clue was found in the crystals collected from Inglefield Land. Unshocked fragments showed compositions consistent with the local bedrock, not unexpectedly. But the shocked crystals and melt fragments show additions to this: they were enhanced in elements such as copper, chromium and gold, and with high rhodium. No local rocks show this and it likely came from the original impactor. Most impactors are made of silicate rocks, but about 10% are metallic, with high iron content. The impactor that made the Hiawatha impact crater appeared to have been such a rare metallic object. Platinum is often associated with iron meteorites, and the spike in platinum abundances at the start of the Younger Dryas had already led to the suggestion of an iron impactor. However, the fragments analyzed from Inglefield Land showed low platinum content, so the evidence did not quite come together.
There were some problems with the idea of such a young age for the Hiawatha crater. The impact would have ejected some 20 km3 of rock, forming a debris layer 200 meters thick around the crater, and 20 meters thick 30 kilometers away. The debris should have shown up in the Greenland ice cores, but nothing has been seen. Could the debris all have been carried away by the ice? Or was the impact under a shallow angle, directing the ejecta away from Greenland?
An association of the Hiawatha impact crater with the start of the Younger Dryas has run into too many problems: the low probability of an impact this size this recent, the lack of evidence in the ice cores and the evidence for 500 meters of erosion of the crater walls point at a much larger age. It may be possible to circumvent the problem by having the impactor hit the ice sheet. Models show that for a 2-km deep ice sheet, a much shallower crater wall and central peak is formed, because the ice absorbs the impact. There is also much less rock ejected from the site. However, this is double the current ice thickness (already amplified by the presence of the crater) and that would put us deep within the glacial maximum, long before the Younger Dryas. A search was made for impact grains in marine deposits associated with the Younger Dryas, but none were found. An association with the Younger Dryas seemed unlikely.
Age
We learned more about the impact from the crystals. The structures of the crystals indicated that the crater cooled rapidly after the impact. Soon after the impact the crater seems to have filled with water. This is consistent with an impact in ice, but it could also be a water-rich, warmer era.
Many of the crystals that were analyzed contain organic material. In one study, organics were seen in 5 out of 6 grains. Carbon dating failed to give an age: this indicates that the organics is older (perhaps much older) than 40,000 years. The material has been identified as coming from burned pine trees. But pine trees have not grown here since the early pleistocene, 2.4 million years ago. Could the crater be this old, predating the ice age altogether, and having formed in a much warmer period? Could it even be the eocene, a warmer period before the world began to cool towards the ice ages?
The controversy around the age was finally resolved this year. Carbon dating is suitable for young dates but not old ones: C-14 decays too fast, leaving nothing after some 40,000 years. But there are other radio isotopes that decay much slower, and these can be used even for geological time scales. Argon is itself not radioactive. When a rock solidifies it has no argon: as a noble gas it escapes the melt. But potassium remains in the rock, and the isotope potassium-40 (40-K) decays (very slowly) into an isotope of argon. Because now it is solid rock, this argon cannot escape. By measuring the amount of argon and the amount of potassium-40, the ratio can be give the age of the sample. The half time is more than a billion years, so that the method works for very old rocks (but not for very young ones!). The second method uses uranium, which over very long times decays into lead. Again, by measuring what fraction of uranium has decayed, the age of the rock can be determined. Because of these methods, we can measure surprisingly accurate ages even for very old rock.
The U-Pb method showed that some of the grains had ages of 1.9 billion year. This dates them to the time when the Inglefield Mobile Belt formed. The map below shows the various ages of local rocks, which agree well with these U-Pb dates for the grains from Hiawatha. (No other rocks in North Greenland have this age – it is unique to the Inglefield Mobile Belt.) Clearly though, this is when the rock formed – not the crater. These grains had not been changed by the impact.
The other grains showed a component with uranium-lead ages around 58 million years, at which time there was a ‘reset’ event which had partially melted the grains.
The argon method indicated ages in excess of 25 million years. The two grains with the best result showed ages of 58 and 60 million years. This agrees very well with the U-Pb method, which shows that ‘something happened’ at this time. This ‘something’ was the impact.
The Hiawatha impact is therefore dated to 58.0+-0.5 million years ago. To put it in context, this was 8 million years after the demise of the dinosaurs, caused by another, much larger impact.
This new age shows that the impact crater has nothing to do with the Younger Dryas, the ice age, or even the pleistocene. It existed long before the ice came. Did the organic remains date from the time of the impact? That is very much plausible: at this time the area was abundantly vegetated at the time and may have had conifer forests. The organic remains became part of the sediment washed out on the river floodplain.
This new age solves the problems that the young ages had: the lack of an ejecta blanket or ice core trace, the significant erosion, and the organic remains. It also leaves the Younger Dryas impact hypothesis without a smoking gun and without its strongest evidence. Unless new evidence emerges, this hypothesis may have to be abandoned.
Impacts
The asteroid caused a dramatic crater. It is perhaps the best surviving example on Earth of a large crater. However, the impact was too small to change the world’s climate or cause a worldwide extinction. That would have required a much larger impact as had happened 8 million years earlier. The effects of the Hiawatha impact would have been major across the local continent, but survivable further afield.
Were there such local effects? It is interesting that the crater is so close to the copper-gold belt which runs parallel to the rim. Did this fault open by the nearby impact? Copper and gold can be deposited by hydrothermal activity: the impact happened in a water-rich region, and the fault could have filled with hot water after the impact? This is of course speculative. The impact was also approximately when the Nares Strait opened. Did the impact break the final connection between Greenland and Ellesmere Island and triggered the activity of the Nares Strait fault? Nearby is an island, which was only recently revealed by the melting ice. It is now claimed by both Denmark and Canada. Perhaps, if this impact had not happened in this place, the two would not have separated and all of the region would now be Danish. It is just a thought.
The era when the crater formed was an exciting time in this part of the world. The volcanism in western Greenland related to the opening of the Labrador Sea occurred 60 million years ago. The paleocene/eocene boundary with its global warming event happened 56 million years ago, related to a flood basalt in eastern Greenland and the opening of the north Atlantic. The Hiawatha impact neatly occurred in between these events. What a time to be alive.
Final point
Dramatic results in science should always be looked at with suspicion, and with an eye to finding confirmation. This is how science works – checking, and checking again. In the end, the data will win. Sometimes, the extraordinary is true. Sometimes, there are changes to the interpretation. In this case, the Younger Dryas impact hypothesis lost out. But we are still left with a city-sized crater no one knew about, hidden in Greenland. The world can still surprise us.
Albert, March 2022
K. H. Kjær et al. A large impact crater beneath Hiawatha Glacier in northwest Greenland. Sci. Adv. 4, eaar8173 (2018) https://www.science.org/doi/10.1126/sciadv.aar8173
G. G. Kenny et al. A Late Paleocene age for Greenland’s Hiawatha impact structure. Sci. Adv. 8 (2022) https://www.science.org/doi/10.1126/sciadv.abm2434
Could it happen again?
Jesper
You don’t need to read this as it is contra-boom. But take into consideration what a charactre Alvarez was, not an Albert, to say the least:
“Keller barely got through her introduction before the audience tore into her: “Stupid.” “You don’t know what you’re doing.” “Totally wrong.” “Nonsense.”
Her first interaction with the community investigating the dinosaurs’ disappearance took place at a 1988 conference on global catastrophes. She presented results from her three-year analysis of a rock section in El Kef, Tunisia, that has long been considered one of the most accurate records of the extinction. Keller specializes in studying the fossils of single-celled marine organisms called foraminifera—“forams,” once you’re on a nickname basis, as Keller is. (She considers these creatures, which include many species of plankton, “old friends.”) Because their fossils are plentiful and well preserved, paleontologists can trace their extinction patterns with considerable accuracy, and thus frequently rely on them as a proxy for other creatures’ well-being.
When Keller examined the El Kef samples, she did not see a “bad weekend,” but a bad era: Three hundred thousand years before Alvarez’s asteroid struck, some foram populations had already started to decline. Keller found that they had become less and less robust until, very rapidly, about a third of them vanished. “My takeaway was that you could not have a single instantaneous event causing this pattern,” she told me. “That was my message at that meeting, and it caused an enormous turmoil.” Keller said she barely got through her introduction before members of the audience tore into her: “Stupid.” “You don’t know what you’re doing.” “Totally wrong.” “Nonsense.”
Ad hominem attacks had by then long characterized the mass-extinction controversy, which came to be known as the “dinosaur wars.” Alvarez had set the tone. His numerous scientific exploits—winning the Nobel Prize in Physics, flying alongside the crew that bombed Hiroshima, “X-raying” Egypt’s pyramids in search of secret chambers—had earned him renown far beyond academia, and he had wielded his star power to mock, malign, and discredit opponents who dared to contradict him. In The New York Times, Alvarez”
Alvarez (Walter) was with the team that bombed Hiroshima. Interesting.
https://www.theatlantic.com/magazine/archive/2018/09/dinosaur-extinction-debate/565769/
One thing is for sure: With the young generations we have now, there is not so much money to be made with Gerta’s observation.
They love boom. And if they don’t change, they might get us into an atomic war at some point, not because they are malign, but because they prefer sensationalism to knowledge and long, tedious schience. And some of the media have helped them to become like that, not the Atlantic, not the Guardian, but mass media.
Not Walter, Luis Alvarez, sorry.
” McLean later wrote on his faculty website that Alvarez’s “vicious politics” had caused him to develop serious health problems and that, for fear of a relapse, he couldn’t research Deccan volcanism without “the greatest of difficulty.” “I never recovered physically or psychologically from that ordeal,” he added. Younger scientists avoided the topic, fearing that they might jeopardize their careers. The impact theory solidified, and volcanism was largely abandoned. McLean later wrote on his faculty website that Alvarez’s “vicious politics” had caused him to develop serious health problems and that, for fear of a relapse, he couldn’t research Deccan volcanism without “the greatest of difficulty.” “I never recovered physically or psychologically from that ordeal,” he added. Younger scientists avoided the topic, fearing that they might jeopardize their careers. The impact theory solidified, and volcanism was largely abandoned.”
That is our science today. Like a battlefied. Summary: “It’s economy, stupid.”
The Deccan Traps had caused adverse conditions for some time. The asteroid hit during a pause in the Deccan Traps. That is how we know the asteroid was the killer blow, rather than the volcano. But a general decline of vulnerable species in the million years before the impact is not unlikely. Neither is the coincidence of the impact and LIP, by the way, When I went through the numbers for both events, I found a 50/50 chance of such a coincidence since the Cambrian. Russian roulette
I have heard, as far as I know (could be wrong) that the impact somewhat accerated volcanic activity after the impact, especially the Deccan Traps and the mid-ocean ridges (even though some would say it triggered it, but I ain’t the buying that), causing a lot more greenhouse gases to be unleashed upon the atmosphere. On that some note, however, that I think the reason why the K-Pg extinction is less severe is because there is a bit more diversity than say at the Great Dying 185 mya earlier. Could be assuming things, but that is what seems to be like.
Could it be that the Cretaceous organisms were simply more vulnerable to severe ecological change than during the Permian? Basically (and especially) the large dinosaurs and their similarly large metabolisms were very susceptible to disruption of the entropic food chain whereas perhaps species in the Permian were a bit more adaptable with respect to their food sources and habitat.
Also making tons of assumptions, but just throwing my thoughts out there.
Authorities in São Jorge, Azores are preparing for a biger quake or even a volcanic eruption… quakes rising in frequency and intensity on last hours.
https://twitter.com/VOSTAZ/status/1506268652147986442
Albert imagine When the sea began to sourge back into the newly formed Chicxulub Crater
The crater impact melt pool 200 km wide and 10 km thick and been many times hotter than the surface of the sun .. some Impressive steam explosions it must have been?
How far away would the impact have been actually “felt” (IE shockwave earthquake, not the pressure wave)? Would essentially the entire planet have rumbled from it?
Seismic activity continues at high levels on São Jorge Island (Azores). Since Saturday afternoon, +1800 earthquakes were recorded on the western half of São Jorge, at least 94 were felt by the population. For detailed information follow SRPCBA and CIVISA.
https://twitter.com/AdrianoAzoVolc/status/1506300074233675788
https://twitter.com/HubGeology/status/1506341055452516353
Overlay of towns with the ongoing uplift at Sao Jorge. Source: latest sentinel run from 19:49 last night. If you live in or near the center of one of these spots, be ready to evacuate with short notice. #portugal #azores #volcano #volcanoes #geology
https://twitter.com/HubGeology/status/1506333617424777219
Recommendation. Officially raise Sao Jorge’s alert level to yellow. Latest sentinel pass revealed actual ground deformation. This deformation can’t simply be explained from earthquake activity and may have a magmatic uplift origin. #volcano #azores #geology #volcanoes #portugal
Thanks for the continuing updates Luis Godinho.
The InSAR does suggest a near vertical dike intrusion which forcefully opens up the ground and pushes up symmetrically the flanks of the island next to the intrusion. The earthquakes could also fit a dike intrusion. So that seems like the most reasonable scenario right now.
So as usual now it is the time to wait and see if, or where, it will erupt.
That cone row up the centre of Sao Jorge uphill from the town of Canada de Africa looks to be the likely eventual eruption area. With uplift, there’s going to be trouble ahead. I hope the locals are on the ball.
I expect that an off-shore eruption is more likely.
Just hope so… people are scary there and local gov is preparing the evacuation of near populations… more or less 5.000 people!
The topography of Sao Jorge, it has such an special shape:
It is interesting to get to see two Atlantic islands erupt (well maybe) within such a short time. Coincidence of course but it is quite exiting. Also exiting in a different way to be on Sao Jorje right now…
It has been a good long time since there was an eruption in the Azores too. Lots of submarine eruptions but none on land for over 200 years if I recall correctly. I wonder if it is the same gas rich fluid basalt as on La Palma, could be quite a firework show.
Sismic station of São Jorge island, Azores
https://wpsmap.com/portugal/sao-jorge/
I hope it is only a lava flow, or even a typical submarine eruption because last time São Jorge erupted, 1808, it erupted effusively at first then erupted explosively, oddly enough. Like, this eruption is weird given that it is in the middle of the island where little to no water could flow into the middle.
It is also an island, and nowhere on the island is that far from the ocean due to the shape. Its not too surprising really when you consider the 1949 eruption on La Palma was partly phreatomagmatic and that was 2 km above sea level and much further in horizontal distance too.
The shape of the island will greatly limit the destruction I would think, anything erupted will just go right down to the ocean, so provided it isn’t a surprise this might not be a disaster.
That is quite interesting. I have remembered on that end-of-dayers show about La Palma where they said that the dikes from previous eruptions are absorbers of water. Obviously, the possibility of a massive landslide on La Palma is near to low as shown by the latest eruption, but could the water on the dikes be a factor in such explosiveness on São Jorge and La Palma?
I think the study was actually of water being trapped inbetween dikes within the porous lava layers, not in the dikes themselves. Not sure how porous the rock of Sao Jorge is, it isnt a stratovolcano so could be quite solid. But then there is explosive activity in its historical record, so maybe it is full of water after all. Not sure the collapse hazard is worth worrying about though it is not a very massive island.
I think every semi-tropical island has such ‘trapped’ water–Hawai’i certainly does, Canarias and Reunion do, too.
I don’t know enough about the geology of Saint Joe, but maybe those pyroclastic flows were simply cone collapses like at Cumbre Vieja and Etna.
I mean a cone collapse and a lava dome collapse are an identical process for all purposes, though a dome collapse can be an actual explosion too sometimes. On Sao Jorge it really doesnt scream an explosive volcano, just very steep cliffs. Fuego is a good comparison, it is really mostly effusive with lava fountain paroxysms, Ulawun too, both basaltic. But they are both so extremely steep the fountain fallout lava, already a lot more viscous and cold than the fresh stuff, it just disintegrates and slides down the mountain at high speed. That is really the very exact description of a glowing avalanche, no explosive element. Explosive part was added when Pelee erupted in 1902 and the dawn of volcanology began.
Damon Hawaii is fully tropical: on sealevel its over 30 degrees C in the shadow even in december..
Althrough also is 12 climate zones on the Big Island depending on altitude and dry or wet side
Azores is semi tropical and haves the mildest and most nice climate that you can ever imagine Oceanic Subtropical
Hawaii is too hot on sealevel for me, But Azores is just right
I understand. I’m never too hot or humid–looking to retire to Houston one of these days.
Kona side: Hot but dry.
Puna side: Warm but humid.
My call: It’s a nice place to visit. 🙂
IPMA – Dynamic map – seismic activity; tab Azores islands https://www.ipma.pt/en/geofisica/sismicidade/
Link To earthquake feed over Saõ Jorge
CIVISA page is better
http://www.ivar.azores.gov.pt/civisa/Paginas/homeCIVISA.aspx
Azores Swarm still going ?
Yes of course. Why you don’t see the live quake link i posted?
That island is banging like a Neil Peart drum solo.
Eruptions on Sao Jorge seem to be long lived, 1808 being about a month and 1580 being possibly several eruptions over about half a year. Maybe to be expected that it is a rifting fissure volcano. It will be quite significant, unpredictable, we could watch it for 2 weeks then it resumes as strong as it started with at another location on the dike. It looks like that occurred in 1808 with the second wave of explosive eruptions forming pyroclastic flows.
Really will be a but if everything, seems the lava is probably very fluid basalt but gas rich so quite explosive strombolian in style, like on La Palma last year.
Yes, the magma is similar to La Palma, although not as strongly alkaline. One big difference though is that La Palma seems to make sill intrusions which sometimes rotate into small radial dikes. Instead Sao Jorge makes long linear dikes due to being in an extensional ares. This could be more similar in style to Timanfaya which erupted from a long dike intrusion. The volcano probably doesn’t have much magma storage so that it will need melt recharge to grow the dike. My guess is that this will cause a slow growth of the dike and thus slow fissure opening.
So Sao Jorge has the potential to open more vents across a large region. The fissure opening will be unpredictable, which combined with water rich explosive magmas, the high population density, and the very steep slopes could make this a slightly problematic eruption. And I do think an eruption is likely, a subaerial one if the dike doesn’t grow much longer. Although the intrusion could always stall and not erupt too.
At least it will not be a lava flood, a rather low intensity but gas rich eruption. Timanfaya was mostly like this but it did begin with a proper lava flood eruption, unusually from only a single vent not a fissure, so there must have been some magma storage though not a lot as that stage of the eruption was fairly brief.
At least the area covered in a potential eruption will be limited, lava will probably rush down to the ocean very fast with little lateral expansion and most damage will be from any ash produced. That is unless it opens under an inhabited area but likely anywhere at risk would be evacuated now the dike is in place and more predictable.
Just saying but Pico island would be a perfect place for a livestream angle, very elevated and safely across the ocean 🙂
So, I suppose the question must be asked–any livecams on Sao Jorge?
Won’t be long before every man and their goat is on their with their drones.
Although – it does have one of the most difficult runway landings in the world.
2022-03-23 (IPMA)
Since 5:00 pm on March 19, a significant increase in the frequency of seismic activity was detected on the island of São Jorge, in the Azores, a situation that has continued until this moment.
More than 1300 earthquakes were recorded in this area of the archipelago, with epicenters distributed in a direction close to the alignment of the island, between Velas and Pico da Esperança. The magnitudes vary between 1.2 and 3.6, with the largest earthquake occurring in the first hours of the seismic crisis. According to the characteristics of the registered earthquakes and the geographical location of the populations, it is expected that more than 100 earthquakes may have been felt, and so far the maximum intensity observed was IV (Mercalli modified, 1956)
The origin of this seismicity may be related to the ascent of magma in a magmatic dyke, a phenomenon that causes fragmentation of rocks at depth, which translates into the release of elastic energy in the form of earthquakes.
IPMA is monitoring the situation by providing all the information to the civil protection system.
If you have witnessed an earthquake, please report it by completing the “macroseismic questionnaire” available at the link below.
Completing this questionnaire is essential to allow IPMA to map the extent of the effects of earthquakes felt.
Looking at the seismic drum chart linked by you earlier, it looks like mostly rock cracking at the moment (in my most monastic humble opinion…). So magma is on the way up, without doubt.
I haven’t seen any depth information for the earthquakes, and I guess that would tell us a lot.
Jesper’s linked IPMA page shows 12-6km at the moment. If Fagradals was anything to go by, we should start seeing fluids on the seismic around 3km. Should the intrusion continue.
I been to Azores and pretty much the nicest climate on Earth very green and pleasant and the greenery is enchanced by using Polarized glasses
Azores haves a very special climate its called
”Oceanic Subtropical Climate” its about around +17 to +24 C depending on season, so very pleasant and mild. Most other Continetal subtropical areras have terrible hot summers .. But Azores out in the ocean remains mild and nice all year around.
Azores type climate is very rare.. only found in a few places at latitude 30 s far out in the oceans. The only other places with similar climate are Madeira, Northen New Zeeland and perhaps Tristan Da Chuna and Norfolk Island wonderfuly mild all year around.
Azores are great for persons that does not like cold or severe heat, as its neither
Not my Photos
The most wonderful climate in my opinion .. Hawaii is too hot for me at sealevel
Nice pictures. Which islands have you been to?
Been to Sao Miguel .. was not as Green as the Photos
But with Polarized glasses on You got that effect for the eyes 🙂 its called the Green Island after all
Sao Miguel haves fantastic hiking, driving trails and beautyful architecture. They haves hot springs and a Geothermal bath
Sao Miguel sits on slow leaky tectonic faults with perhaps some kind of weak mantle plume flow from the West, Volcanism on Sao Miguel is very sluggish and tired, But the Island is not dead by anyway. Its composed of three active But tired volcanic caldera centers and alot of monogentic cinder cones
I doubt that Sao Miguel will erupt anytime soon, Sete Cidades, Augua De Pau and Furnas are the main caldera centers
Thank you. I might travel there one day, not so hot. Hawai’i I can’t do.
Alert level in São Jorge, just rised to 4 in 5. Authorities hasked to people get ready to evacuate anytime!
São Jorge page on volcanodiscovery…
https://webcams.volcanodiscovery.com/SanJorge
Looks like the active area is in the same areas as the last two eruptions on land, and very close to the airport, which could turn this into a big problem. Unless there are ports elsewhere on the island it might be very hard to access, so most pictures could be from a distance this time.
Do you think its going To erupt ?
At this point yes
Yes there are ports and two big boats ready to evacuate people… emergency plan just got activated…
Azores sits on thin litosphere so the magma thats now intruding into Sao Jorge is probaly hot and fresh stuff ( Pico can produce very fluid alkaline pahoehoes ) in Azores its generated in small ammounts by decompression melting in leaky faults and with some kind of weak hotspot.
Will be very fast Aa lava flows down these steep Fajanas, low in sillica and most important high in temperatures
There was a well studied long term submarine eruption in the Azores at the turn of the century, the lava erupted there was very low viscosity. The lava of Fogo in Cape Verde and basalts in the Canaries are all pretty much physically the same, low viscosity but high volatile content, so much more fountaining at a lower intensity and a lot of ash.
Saint George’s EQs aren’t shallowing with time. I’ve seen one at 6 KM with the rest at 10-12 KM. The frequency seems low, too.
Not many people know this, but earthquakes tend to concentrate along the base of the dike. I have seen data for many Kilauea dike intrusions where earthquakes always happen along the base of the intrusions 2-3 km underground and offset to the south, because Kilauea dikes always have reach down to that depth and dip southward, something that has been modelled from deformation data too. There is also nice relocated data of the Holuhraun dike showing eqs along the dike base.
For Sao Jorge the bottom of the dike would be at 10-12 km where the earthquakes are happening. The top of the dike instead is aseismic. The depth of the earthquakes is thus a poor indicator of how close the magma is to the surface because they actually indicate the bottom of the intrusion. This makes it difficult to predict a the first outbreak, when or where it may happen.
Although this is only for simple dikes. It might not hold true for other types of intrusions and magma movements.
Piton de la Fournaise for example has a ring of earthquakes surrounding its magma chamber. When it makes an intrusion, one side of the this ring flares up with seismic activity, and the side points in the direction taken by the intrusion. The intrusion starts as a sill and then rotates into vertical. So it is not too straightforward the way that volcanoes make their earthquakes.
Albert,
up to now I haven’t understood this: “Neither was it a large, 10-km crater.” Is it possible that you forgot a zero?
No. 10 km is large. The point here is that even a large crater could have comfortably fitted under (and hidden by) the glacier. But that wasn’t the case. The entire glacier was the crater: it was much bigger than 10 km
Yes, I wondered the same. Maybe “Neither was it a large, 10-km crater. It was even larger, …”, or such a phrasing would have made the intention clearer? But in any case, a great article from you, as always. You have a talent for depicting geological time scales almost lyrically, thanks!
(BTW. Have you ever read Olaf Stapledon?)
Q. to who feels he can answer this: Is it possible with this accumulation of quakes that an eruption is already going on, but submarine? Would that be realized right away?
What the Tanis Site looked like going through Chicxlulub .. the ejecta atmospheric heating firestorms and the Impact Winter and the recovery after in the early days of Paleocene
http://www.sciencephoto.com/image/c0257657/800wm
Well, a bit artificial. It is supposed to have been subtropical before, so maybe we should imagine it a bit like Hawai’i and yet different, having been muddy, containing Maastrichian clay and sandstone whereas Hawai’i is volcanic. Warmer certainly than the Azores, but never really cold. Hell’s Creek (not de Palma’s site Tanis, Hell’s Creek is much larger), has been known since the sixties and has plant and animal fossils covering a period of 2-3 million years, corresponding to a long meteorite, joke.
Quote: – The entire Hell Creek Formation represents somewhere between 2 and 3 million years, Horner said. If it turns out to be 3 million, he expects to see some evolutionary change throughout the formation. “If it’s less than that, we probably wouldn’t see very much.”
https://www.montana.edu/news/9301/paradise-in-hell-creek
Tanis (de Palma) by contraste is basically testimony of a flash flood/tsunami as they are all washed up in one place. Ron Blakey shows the Western Interior Seaway closed at the time, open though some 5 million years before, so it might as well have been open as Blakey says himself that paleographic maps have hypothetical elements, the older, the more.
As there were also crocodilians it was decisively wet and muddy.
The distance to the event seems to play no minor role as seen here:
“Insect predation on fossil leaves shows a considerably more rapid recovery from the extinction in event in Patagonia (about 4 Ma) than in the Western Interior of North America, estimated at 9 million years.”
https://en.wikipedia.org/wiki/Lefipán_Formation
This is pretty interesting as well:
The Berivotra Formation appears to include near its top a magnetic reversal, interpreted as the shift from Chron 30N to Chron 29R, which occurred approximately 65.8 million years ago (about 300,000 years before the Cretaceous–Paleogene boundary and associated Cretaceous–Paleogene extinction event. This suggests that Maevarano organisms also lived shortly before (geologically speaking) the extinction event.
This is Madagascar.
https://en.wikipedia.org/wiki/Maevarano_Formation
I am not buying into the global burndown as there were oceans, albeit the Atlantic Ocean narrower, but Tethys still present plus side oceans of Tethys, a gigantic bay or seaway between North and South America and then a giant Panthálassa/Pacific O. adding to this a tsunami of several hundred metres (some figure up to 1000) raging around the world for several days which means: Everything was wet like a cockpit in a storm, the trees were taken down by the waves, when the tsunami was finished it was dark and became cold with sour rain. If it burned right away the tsunami was the fire brigade. Many eggs died. Eggs need warmth. Mammals survived. I wonder what the avian dinosaurs did with their eggs, and whether they were able to choose a warm place, like near the Deccan Traps or other volcanic provinces.
It needs to be kept in mind though that this event was a multiplication of Laki or Krakatau, with not enough sun, growth and food for several years.
The monster tsunamis woud have only impacted the coastal regions and drowned them .. the land interiors where competely dry from that, But you right still enormous waves and They left their tsunami deposits in the Mexico coasts that can be seen today in outcrops
Chixlulub ejected alot of ejecta perhaps ( 50 000 km3 ) and sent that at hypersonic speeds over the upper atmosphere.. as it comes in from Space as trillions of mini meteors it heats up the upper atmosphere to flash point … anything on the ground woud have burst into flames from that Thermal radiation
Most of the ejecta never made it to the ground But it woud make the skies very hot as it reenters, there is a global soot layer deposits suggesting that most of the biosphere burned. The ejecta woud have travelled all over the planet as it skids the upper atmosphere 80 km up at high speeds.
The ejecta high up in the atmosphere can be thinked of an oven heating element grill
The worst effect from Chicxulub was the Impact Winter, I been reading about 23 C drop in temperatures, that must have been bad thing for These greenhouse adapted bioforms, even if many dinosaurs had feathers and endotehermy. Ultimately the winter and the shutdown of the photosyntetic food chains is what killed off most large KT animals.
Hawaii is competely tropical at sealevel
The Subtropical Swamps of Louisiana and New Orleans and Florida is probaly the best analouge to Hell Creek Today in the What it looked like
Louisiana is a good comparison or maybe the Everglades.
You can even see the traces of the tsunami by the much smaller (est. 1-4 km) Eltanin neteorite in the Bellinghausen Sea around South America.
Only the coastal regions is questionable. I read that Mega-tsunamis go far inland, and don’t forget, like humans many animals lived near the coasts.
Hell’s Creek is dry and hot today and people digging there complain about snakes. Maybe that’s why the snakes i.e. survived.
You woud see a furnace orange sky packed with very bright white hot streaks that streams down all the time perhaps the ejecta is so dense that the skies became really white hot and surface temperatures well over 1000 C over parts of the continents for a short time after Chicxulub hit. North America became totaly burned clean .. from vegitation in many outcrops in micro – fossil studies of KT sediments
Most models of Chicxulub global atmospheric heating puts it at over 550 C for some time and perhaps 220 to 300 C for isolated parts of Sourthen Hemisphere
The main heat pulse lasted only two days in most models
Soil and Sand are very good insulation .. so small animals where fine hiding in the burrows
Well it lasted most of it less than a day … But atmosphere had higher than normal temperatures for many days
After it cools down .. the Impact Winter starts and things starts to Freeze Instead
Swimming in the ocean coud work too .. and That woud allow you to surivive very close to Chicxlulub Impact .. If you are 200 meters down in scuba tanks .. You woud be safe from the Impact Flash and the ejecta heating
Jesper,
Any sources you could share about the climate changes following the impact event? I don’t think I’ve ever seen anything on the subject and it’s fascinating. A 23C drop is *massive.*
Thanks man,
Ryan
Unsurvivable is the word you are looking for. I am not sure where it comes from, and have some doubts about it. You can’t easily get such a drop on Earth unless you increase the albedo (reflectivity). Dust won’t do it. Sulphate can do more but is not something particularly associated with impacts. Land temperatures are of course much more variable than ocean temperatures, because of the low heat capacity of land. Perhaps it refers to this
As Big as the Chicxulub Impact was
Its still small compared To the Impacts during Earths Formation.. When whole protoplanets merged at high speeds
Still a Chicxulub sized event woud be mayhem today .. and shut down most of the civilization altogther.. perhaps only a few hunter gatheres woud made it, But Humans are more intelligent than the dinosaurs and can Prepare. But it woud still be catastrophic of it happened today
I guess an asteorid just a little larger than Chixlulub Impactor woud make most land life thats not insects extinct
Well, humans can plan, but they have a huge problem: Electricity and Atomic Power. So, a meteorite this size which won’t arrive for the foreseeable future needs to be given another trajectory, and here we must strongly hope for science (NASA and so on).
Hiawatha Crater was formed during one of the warmest eras in Earths history of complex life
The Paleocene.. the world was as much as
+13 C warmer than today with +30 C as global avarge
Paleocene and Early Eocene was a supergreenhouse with even the poles where almost tropical during the warmest parts of the PETM. Antartica had baobab and coconut palms growing on its shores 58 million years ago, same as Greenland and crocodiles swam in the Arctic Ocean
Most of Earths landmasses where completely covered by tropical rainforest back then and mangroove forests lined the shores of the Arctic Ocean. The world was wetter and more humid because of more evaporation and cloud formation from warmer oceans
Sea surface waters near Equator reached 44 C during the PETM competely crazy
The Pantanal?
Yes and thats what Sweden probaly looked like back then .. But all sedimentation from PETM been scraped from Sweden by the later Ice Ages
La Grande Coupure is interesting as well, interpreted as global cooling, possibly preceded by Popigai and Chesapeake which might have a second part on the Atlantic Ocean shelf east of Atlantic City, Rom’s Crater.
Nobody read this, otherwise I’d stand corrected with Tom’s Crater
What I’m just starting to think about is whether the whole structure was flatter. For sure the Himalayas weren’t there, neither the Alps, nor the New Zealand Alps. The mountains in the Caucasus, nope. Morocco was separated from Africa by a seaway (mososaurs found there), so the Atlas mountains weren’t present. The Transpangaean Mountain Range was about 180 million years into erosion.
The continents were separating, some were submarine, orogenies result from collisions and subduction. China was smaller, possibly still two parts, Japan wasn’t there. The sea levels were much higher.
This means a tsunami has to be looked at under different conditions.
There were certainly volcanoes, but possibly not as many mountain ranges as it was a time of divergence contrary to the end of the Perm.
Azores
I was wondering whether something is going on in the submarine realm instead.
The setting:
An ultraslow spreading ridge, the Terceira Ridge, comparable with the Gakkel Ridge, Sao Jorge neatly aligned parallel to the ridge:
“The combined interaction of a high obliquity, very slow spreading rates, and a thick preexisting lithosphere along the axis probably prevents the formation and eruption of larger amounts of melt along the Terceira Rift. However, the presence of ocean islands requires a relatively stable melting anomaly over relatively long periods of time.”
https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2008GC002112
“252 submarine volcanic cones mapped so far……They are distributed in water depths of 120 m to 3200 m. Based on a combined morphological and seismic interpretation, all of them are associated with explosive eruptions.”
https://www.sciencedirect.com/science/article/abs/pii/S037702731500236X
Azores is a plate boundary region combined with a mantle plume .. a little like Iceland
But the Azores are mostly leaky transform faults and the plume are waaay waay weaker than Icelands
Azores Plume is perhaps dying and fading over Long timespanns its been active for 25 million years I think When it first started to form the Azores Igenous Plateau
The Islands are very much depending on these leaky faults where most of the magma can emerge through, all of the Islands are younger than 5 million years
More precisely we find a Triple Junction between the American, the Nubian and the Eurasian Plates . East of the junction we have an ultraslow Spreading Ridge of a length of about 500 km, the Terceira Ridge, immediately north of the Azore Plateau, running ENE-WSW and then in the North-east, ending in the The Azores–Gibraltar Transform Fault (AGFZ).
This is very different from Iceland as the Terceira fault is running roughly perpendicular to the MAR, and Iceland only has two plates meeting.
The prolongation of the ridge, the AGFZ, is known to cause huge earthquakes with consequences for the continent (Lisbon Earthquake). Iceland, as far as I know, doesn’t cause problems in Norway or Greenland.
This is also quite different from the Canary Islands as there are no plates meeting there.
It might be similar to Galápagos though with its own Triple Junction (Nazca/Cocos/Pacific)
Yes right …
Althrough Galapagos Plume is not on a plate boundary at current location and Galapagos is much more powerful as a plume as well
Volcanism in Azores is sluggish
Hmm, I do think triple junctions attract anomalous amounts of magma but there’s little to no evidence of a plume head there. The geology of the Azores volcanoes is very rift-driven.
Without somekind of plume the faults may not be able to produce enough magma to form Islands.. but the Azores Plume is also a weak one it formed the Azores plateau 20 million years ago
Oh, I don’t know about that. Think of Japan or Hunga-Tonga-once been.
Quakes are getting more shallow now
Well Im reading the data wrong
Its not going to erupt .. mostly represent magma thats risen to the base of the oceanic crust .. but who knows ..
It wouldnt form a dike if it was that deep, those only form in the crust and in brittle crust too. It could be leaking up a deep set fault but in that case it is only going to make it rise faster.
Not sure if you saw Hectors comment before but quakes trace the bottom of the dike so the bottom of it is still brittle enough to quake. There could be multiple dikes, the shallowest one bottoms out at 6 km so the top could be a lot shallower. Not a certainty it will erupt but usually these sorts of places erupt from overpressure and there is not much room underground to go so the chances are high that this will erupt.
What I like best about that video is that the author does give sound advice for anyone in a possibly affected area. Good move!
Essentially, document what you have in case you need that info for a claim, while you still have plenty of time to do it, and make a “go-bag” so you can beat feet within 5 minutes if ordered to evacuate. And my favorite…. stay away from anything that erupts.
My Azores experience was basically sitting on the ship while we drilled holes in the water while the Helo moved passengers. Pretty islands… as islands go.
Friday
25.03.2022 07:02:33 64.619 -17.385 0.1 km 4.1 99.0 7.2 km ESE of Bárðarbunga
Many quakes on La Palma since yesterday too…
Regarding São Jorge quake swarm, things are a bit more calm since yesterday… quakes less energetic.
The calm before the storm…
It is an area of intense earthquakes, also swarms.
The 1964 Rosais Earthquake was in the same area, a lot stronger though.
The 1998 Earthquake was close and even closer to Faial. It had a magnitude of 6.2 and about 10.000 aftershocks over a period of four months.
On December 31st 2021 there was a larger earthquake further west close to the MAR with a magnitude of 5.
Aside from that there are obviously 252 mapped seamounts.
Volcanism might not even be that rare, but happen around the seamounts. Considering how little of the crust is subareal this also made me think of the larger, but mainly submerged Kerguelen Plateau, not too far from the Rodrigues Triple Junction.
Heard, Kerguelen:
Wikimedia Commons
Taal just had a Phreatomagmatic burst, and I am still frustrated that I am no closer to understanding why there hasn’t been more substantial eruptions despite the incredible deformation and gas emissions.
Volcanoes are in no hurry. They’ll erupt, eventually, when you least expect.
Geological timescales We are but specks of dust.
I became interested in Sabancaya and Ampato in between as there was an earthquake of 5,4 magnitude there 13 hours ago, but alas, it was in a depth of 98,5 km (greetings from the Nazca Plate?). Anyway, interesting area, with two dormant and one extinct (believed) volcano, Hualca-Hualca.
Arequipa, a colonial city, with Misti and three other volcanoes is about 80 km to the south.
I found an interesting report about the vulnerability of Arepiqua:
https://perureports.com/arequipa-is-one-of-the-most-vulnerable-cities-to-volcano-in-the-world-study-shows/8198/
Amazing lava flows, aren’t they?
Picture wikimedia commons
I love lava flows. When seen in Google Earth they are amazing too.
Hualca Hualca may look dead but it is actually inflating. It might be that Sabancaya is a satellite vent of Hualca Hualca.
Very interesting, thank you, Héctor.
I wonder if the activity at Sabacaya now is precursory to another phase of shield building. I also do say shield building, it is effusive and the lava flows a long way despite the viscosity, so the eruption must have lasted a long time at low rate. Looking at Ampato it is another effusive volcano though a lot older.
One of the things I noticed about these massive silicic provinces is that most eruptions are effusive until the whole thing goes caldera, it isnt like normal arc volcanism which is properly explosive but rarely anything major. Even in explosive eruptions often that is followed by a more voluminous dome building stage, looking at Okataina for example it erupted a VEI 6 about 5800 years ago but followed that with over twice that DRE of effusive rhyolite. In recent times both Puyehue Cordon Caulle and Chaiten started as VeI 4-5 plinian eruptions before going effusive, and erupting more lava than the ash DRE volume.
All the books and basic sources say basalt is effusive and rhyolite is explosive but effusive felsic volcanism is a major category, while most of the VEI 4 scale eruptions are basaltic. Plume basalt is effusive but arc basalt has a lot if water, while chances are the millennia it takes to accumulate means a VEI 8 magma chamber is going to end up degassed, the eruption mostly driven by the immense weight of the caldera block falling into the chamber. If the 5% drain rule seen from Kilauea is a standard a VEI 8 could be triggered by a shallow magma chamber of 1000 km3 undergoing a VEI 6.
Silicic volcanism is often mixed effusive explosive. Sabancaya has a lava dome in the crater which often blows up, if the lava level was high enough it would overflow making lava flows. It is like an oversized spatter cone. The lava dome is like the roiling pond in the mouth of the spatter cone. The explosions are like oversized bursts of spatter. And the lava flows are like narrow pahoehoe lobes reaching out from the vent. I’ve always thought that the statement that silicic magmas are more explosive is a bit misleading. Silicic magmas simply make things happen on a bigger scale, and are thus more dangerous.
Though it is a complex matter given that it is true that silicic magmas tend to fragmentate more easily due to their viscosity, and often have more water than basalts. Water drives explosivity.
Particularly the difference is very big with oceanic ridge basalts. Some mid-oceanic ridge basalts may have as little as 0.05% water whereas a subdiuction zone rhyolite may have something like 6% water. So there are many factors. Potassic and in general continental basalts are higher in water, levels like 2-4 % water are common in continental basaltic magmas or those with potassic affinity like Azores or the Canary Islands. Kilauea instead is about 0.4 % water, in between a mid-ocean ridge basalt and a continental one.
I did notice looking at spatter cones both on Kilauea now and also in 2018, and at Fagradalsfjall too, spatter cones are like tiny lava domes as you say. Rhyolite lava is like a pahoehoe toe on a huge scale too.
On the thermal cam you can see a spatter cone on the east side if the crater forming its own tiny lava shield every now and then, it was quite active yesterday.
I also noticed that the pyroclastic cones made at fluid basalt vents often have semi-molten cores and especially during high fountains will flow just like a lava dome flow. This was especially obvious on La Palma. These fountain cones like Pu’u O’o and the SEC on Etna are basically small stratovolcanoes. Those two are satellitic to a bigger volcano but I guess if you get one of those that is standing alone you can make something like Nyiragongo or Klyuchevskoi. Fagradalsfjall could have turned out like that too if it kept going.
Yes and very viscous too, blocky flows seen from space, 100 s of meters thick, like magmatic glaciers almost they erupted
Is Sabancaya a parasitic cone of Ampato?
Héctor said possibly of Hualca-Hualca.
Kilauea getting interesting. Not imminent yet but the system is beginning to pressurize, there has been noticeable inflation on the GPS and now there also might be a sign of magma at Pu’u O’o for the first time since September last year. It is basically the same signal as preceeded the eruption only that the eruption has not actually stopped at all, or even slowed down.
Might be quite a show for me to see 🙂
New CIVISA page regarding São Jorge crisis
http://www.ivar.azores.gov.pt/sjorge/Paginas/default.aspx
Aaa so No magma then .. its just tectonic quakes they say
No they don’t say it. It’s a volcano-tectonic event. And the magma is rising…
The swarm is not dense enough to be a magmatic intrusion
Are They really soure magma is rising? Using Google Translate I can only read that its of tectonic origin
Anak Krakatau erupted yesterday. Looks like it’s rebuilding south/central.
Ruapehu also had a temperature increase coinciding with volcanic tremor. Alert level was raised but an eruption still unlikely as yet.
LOOKS LIKE TAAL IN IN ERUPTION MODE AGAIN
Started 20 minutes ago
Philvocs raises alert level to 3
http://www.xinhuanet.com/english/asiapacific/20220326/187e39e8e65547b3885c683ae509e24d/c.html
Sao Jorge preparing for an evacuation
https://weatherboy.com/volcano-alert-level-raised-while-authorities-prepare-for-mass-evacuation/
In the midst of my sleep I started thinking about dikes. About the December intrusion of Fagradalsfjall and the recent intrusion of Sao Jorge. So I’ll share my thoughts, and my drawings.
Back with Fagradalsfjall in December I was surprised by how fast the dike grew horizontally, in a matter of hours only, versus how long I suspected it would take to reach the surface, a month or so like with the preceding Fagradalsfjall eruption. Sao Jorge has again surprised me by how fast the swarm of earthquakes spreads horizontally versus how much it takes for the intrusion to breach the surface. Last Sao Jorge eruption of 1808 took a week to make way for the surface. That is why I’m starting to think that a dike grows horizontally first before sending up a series of lobes upwards. It kinda also matches with how fissure eruptions happen from a series of separate fissures that do not align perfectly with each other and open at different times. Presumably as certain lobes reach the surface. Think how in Fagradalsfjall fissure openings occurred days appart. Anyway so I think that typical dike representations might be too simple, so I started drawing some imaginary intrusions. I think they might be more realistic in shape, although who knows though:
This could be Timanfaya, Fagradalsfjall, of some Kilauea intrusion:
This is inspired by the Sierra Negra intrusion of 2018, a sill fed eruption:
Something more complex:
That 3rd picture does remind me of some of the fissure swarms of Kilauea look in my map. Generally magma moves east but there are some places where vents ecist that allign bettwe with fissure swarms from further downrift, which would imply a dike that intruded westwards within the ERZ from the presumed center of the relevant fissure swarm. I have not been able to confirm the presence of actual magma chambers in those swarms, really those only exist at Makaopuhi and Napau, but it seems likely there are some other storage areas just smaller. Such ‘backwards’ intrusions also did take place in the 1970s and 1965, into the Koae faults, so it happening further east is not so unlikely.
The 1974 eruption of Kilauea, both the one at Keanakako’i and down in the Kau desert, those also seem of the complex type.
Interesting postulation. It makes sense, when one considers why/how the upper chamber formed in the first place?
If I understand your thinking correctly, it may be that as magma from a deeper source/plume starts rising, it will continue to do so as long as it can penetrate the overlying rock/crust…generally through a series of dikes or fissures. However, when/where the plume cannot penetrate any further (vertically), the rising magma then starts to accumulate, thus forming a reservoir at shallow depth that spreads laterally in the form of sills. As the sills continue to spread/expand, where ever the sill encounters weakness in the crust above, magma then follows this weakness to form a conduit or dike that eventually breaks the surface as a volcano.
A good example would be a “sprinkler hose”, which is a hose with many micro-holes in it; but in this example, there is an ultra- thin film covering the holes. As the hose inflates (think of it as an upper magma chamber), pressure builds and eventually the thin film over one of the holes fails and water starts shooting out as an “eruption”.
Anyway, that’s how I visualize it….and thanks again fer your thoughts on the subject.
The first sketch looks a bit like Shiprock, New Mexico, but maybe the lobe like structure is just an artefact of the erosion.
https://www.nasa.gov/image-feature/jpl/pia21266/wing-dike-of-hardened-lava-in-new-mexico/
Azores continoues to quake 13 kilometers down, been many this morning, caused by magma?
Wow
UYv1VDrb0niW.jpg
São Jorge Island (Azores): volcano-seismic crisis continues as scientists conclude magmatic origin, raise alert level
Sat, 26 Mar 2022, 07:47
https://www.volcanodiscovery.com/san-jorge/news/176285/So-Jorge-Island-Azores-volcano-seismic-crisis-continues-as-scientists-conclude-magmatic-origin-raise.html
Something of an interesting question. Looking at Kilauea right now the lava flow is vigorous but sort of just stops advancing. Same thing happened at Fagradalsfjall a lot too the lava would seemingly just disappear into the older flow surface. But it doesnt happen on much older ground of a few years or more. I wonder if fresh basalt is so porous that the lava can just seep back into it, and that most basalt rock found is slightly metamorphic and altered.
Maybe not always, the deep channel down near Kapoho did have a substrate of very solid basalt but the surface level stuff is vesicular and light as a feather.
Idea is very similar to water flowing over wet sand.
Yes must be flowing into cracks in the lava crust on the rootless lake
Taal got raised back up to alert level 3 today:
https://www.phivolcs.dost.gov.ph/index.php/volcano-hazard/volcano-bulletin2/taal-volcano/14331-taal-volcano-eruption-update-26-march-2022-07-45-pm
Tremor is rising. Could be another VEI3/4 blast. The biggie is hundreds of years away.
Swarm still going in Azores
Entire chain shaking since last weekend (with the exception of Flores:
https://weatherboy.com/evacuations-begin-as-seismic-crisis-unfolds-in-atlantic-threats-of-volcanic-eruption-toxic-gases-landslides-and-tsunami-discussed/
1.250 inhabitants left the island by themselves. The earthquake mag 7 in 1757 killed 1.500 people, the volcanic eruptions in the 16th century only eight, in the 19th century ten.
A larger earthquake is the bigger hazard without any doubt.
https://earthzine.org/geological-hazards-and-monitoring-at-the-azores-portugal/ has good information on the Azores. Looking at Fig 5 one is tempted to say that it pointed a finger at Sao Jorge as being next due to the paucity of quakes, as well as the southmost island
New post is up. Lurking on sulphur
https://www.volcanocafe.org/cso/