Iwo Jima in 45 eruptions

/ 12/10/2018

Iwo Jima has long been of particular interest to VC. It is an enigmatic volcano with a very human history. One of the pivotal battles of the second world war took place here, at immense human cost which arguably changed the way the war ended. The island remains home to the Japanese navy, and visits are restricted to those coming for memorials – of both sides. The people who visit find many reminders of the past. But in spite of the memories, the island has changed. The beach where the US marines first landed is now more than 10 meters above sea level. The island is also larger than it used to be. The volcano below is stirring.

Early September there was a report of increasing earthquake activity, which was followed by a minor eruption on September 12. It happened just off the south coast, and witnesses reported seeing water fountaining 10 meters high. But no pictures have emerged of the eruption, and after the event things quickly calmed down again. In itself, this was a normal event. Iwo Jima has such minor explosions every few years, sometimes on land, sometimes off the coast, although they have become much more frequent over the last decade.

We have found one (and only one) image which caught the effect of the eruption. A SkySat satellite photographed half the island on Sept 13. It uncovered strong discolouration in the water, on the south side of the island, in the general region where the fountaining was said to have occurred. Older images show nothing similar in this location, and it is likely volcanic ejecta. But the exact location of the outburst is not clear from the image: it will be either inside the coloured patch or just to the right in the region that was missed.

This post aims to bring together what is known about Iwo Jima, which perhaps is less than we should know. It is an extraordinary place, where the long-term inflation is among the largest seen anywhere in the world. The inflation is clearly volcanic: since 1889, 45 separate eruptions have been recorded. It deserves a closer look.

History

But first some background. The Volcano Islands (Kazan-rettō in Japanese) are a group of three small volcanic islands,of which Iwo Jima is the middle one. North of it is Kita-Iō (San Alexander Island), and south of it Minami-Iō (San Augustino Island).

Iwo Jima was (probably) discovered by the Spanish sailor Bernardo de la Torre, in 1543. On September 25, ‘they had sight of certain islands which they named Mal abrigos [‘bad anchorage’]. Beyond them they discovered Las Dos Hermanos (Two Sisters). And beyond them they also saw four [or three] islands more which they called Los Volcanes’. (Edited from Thomas Suarez, early mapping of the Pacific, 2013. For a more detailed report of the expedition, see the bottom of this post.) The first two islands are believed to be the Daito islands, and the last four or three islands are assumed to include Iwo Jima. Various sources state that he landed on Iwo Jima and named it Sufre (or sulfur) Island, but this appears not to be true: no landing is mentioned and the name was given by Cook’s expedition, two centuries later. In either case, the name has stuck: ‘iwo’ is sulfur, and ‘jima’ is island. (There are a number of ‘sulfur islands’ with a similar name, and it is not uncommon that an image of the wrong island accompanies a report on Iwo Jima. Anything showing a smoking volcano should immediately be discarded.) The official name was changed in 2007 to Ioto, and this should reduce the confusion. The new name has the same Japanese characters and meaning, but a different pronunciation and it is argued to be more historically correct. It will be hard though to remove the name Iwo Jima from memory. Too much has happened here under that label.

Captain James Kirk Cook is reported to have investigated the island in 1779. His journal contains a rather discouraging description of the (re-)discovery of the island:

‘Between 9 & 10 o’clock we passed by the island within a mile from the shore, and as it appeared to be barren and uninhabited we kept on our course without making any stay on it. At the southwest point of it stands a round hummock which appeared to be a volcano as we saw some brimstone on it; at the north east point stood a number of remarkable rocks close to the beach not unlike in their appearance to Stonehenge; the island is about 6 or 7 leagues in circumference & the land low & much of it covered with low shrubbery but no trees of any kind. ‘

A remarkable detail is that this was on 15 November 1779, which is 9 months after Cook had died; there must be some doubt about his involvement! This discovery from beyond the grave was in fact done by James King and John Gore, who had taken joint charge of the expedition. The discoverers were sailing north to south, so the fact that they picked out the southwestern point as the notable feature means it really stood out. The expedition did not land on the island, in contrast to what is claimed on wikipedia. The journal states that Iwo Jima is one of three islands they saw. De La Torre may have seen four.

The journal of Cook’s voyages (authored by William Bligh & James Cook) contains drawings of the island. They show the view towards the east-northeast. The ‘hummock’ dominates, with a low neck and a rocky dome. At the far end there are some rock plugs on a small dome, only just above sea level, with presumably formed the ‘Stonehenge’ feature he refers to.

The map of the island shows the thin neck, the two high areas, and the surrounding shallows. It also indicates three areas further from the coast which presumably are rock reefs.

The basic features that Cook found still exist. They have acquired names since. The southwest ‘hummock’ is called Suribachiyama (or Mount Suribachi). The round dome is Motoyama, and the sandy neck in between is called Chidorigahara.

The risen land

But even though those features are still there, much has changed. On Cook’s profile of the island, Suribachiyama stands around 2.5 times higher than the highest point of Motoyama, and Chidorigahara is only just above the water line.

The recent situation is shown below, using profiles re-published by Kenneth LaJoie, in 1986. They show Motoyama almost as high as Suribachi, and Chidorigahara 40 meters above sea. Surabachi is currently about 160 meters tall. If it was this high also in Cook’s days, the old map suggests that at that time Motoyama was 60-70 meters tall. Nowadays it rises to 120 meters. Chidorigahara has gone from near-zero to 40 meters above sea. The conclusion is that much of the island has risen by 40-60 meters since 1779, where Motoyama has probably risen a bit more than Chidorigahara.

Source: Kenneth R.LaJoie, Coastal Tectonics (1986, published in “Active Tectonics: Impact on Society”.

The recent data shows the beach lines of the past. The one labeled ‘1779’ is suggested to be the beach seen by Cook, assuming that Motoyama and Chidorigahara have risen by the same amount (in reality, Motoyama is likely to have risen more). The line labeled ‘0.5-0.7 ka’ is for a layer which contains carbon-dated coral. Clearly, this layer was below water when the coral formed, somewhere around 1450+-100 AD. Nowadays, it is 100 meters above water. But the entire top of Motoyama shows coral fragments and rounded pebbles, showing it was entirely under water until quite recently.

So Motoyama has been coming up at an average rate of 20 cm per year, over at least 500 years! If Bernardo de la Torre did indeed see the same island, it must have looked a very different place, with Suribachi and Motoyama forming two separate islands. Perhaps this is why he may have reported four islands where later explorers found three (but see the bottom of the post).

Growing up

Iwo Jima. August 2018

The island has not only grown up. It has also grown out. The most current image comes from a satellite view obtained in August 2018. I have attempted to put the old map of Cook on top of the current view. This was done by assuming that Suribachi and Motoyama haven’t moved, and using these to align the two images. The overlay may not be perfect!

The comparison shows how much Chidorigahara has widened. Much of the dotted parts of the old map, indicating shallows, are now land. The east and west side of Motoyama have especially grown. The northeast coast, where the old ‘Stonehenge’ must have been located, has not moved as much. The coast here is quite steep.

The rock reefs are an interesting problem. One of the reefs on Cook’s maps, Kamaiwa, has become incorporated in the beach (this happened around 1968). His two other reefs have disappeared. Two new features have taken their place. On the west, there is a new island (called Kangoki-iwa) which is close to merging with the main island, and on the east side there is a new reef (Higashi-iwa) where the rocks come up to just above the water line. It is a little suspicious that two reefs have gone missing while two new ones have come up. It is possible that both were misplaced on the map.

The rocks of Higashi-iwa

The growth of the island has been followed now for over a century. Below are a series of maps compiled by Norio Oyagi and Takashi Inokuchi, and published in Geology of Iwo Jima. The maps depict the changes between 1911 and 1983. Until 1952, the coast line was fairly stable, apart from a slight extension on the west side. After 1952, growth took off. The changes on the west became spectacular. Cook’s old reef which since had acquired the name of Kamaiwa used to be 1 kilometer off the coast. The channel between it and the coast was 36meter deep and navigable. After 1952, the beach extended into the channel by as much as 50 meters per year, and in 1968, Kamaiwa became connected to the coast. Beyond it lies the island of Kangoki-iwa. It used to be more than 1.5 kilometers from the coast, far enough that it was used to house prisoners. The shark infested waters provided an escape proof barrier. By 1983 Kamaiwa formed the closest part of the coast. The beach has continued to grow since, and in the 2018 image above, is only a few hundred meters from Kangoki-iwa. Escape finally beckons for the prisoners, albeit too late to be of any use.

Why did the beach extend so quickly and by so much? This was more than just uplift. It turns out that it was related to the uplift of the coast to the north. The steep coast line here eroded while it was uplifted, perhaps hastened by the regular typhoons (several pass though here each year). The eroded sand was moved by the current and waves, and deposited on the west side. Sometimes the sea just can’t win. But it does try.

This image (from iwojima.com) shows the typical lineation of raised beaches. Look above the cliff, and the lineation continues in the rocks, suggestive of earlier periods of wave erosion.

Activity

Iwo Jima is doing more than just grow up and grow out. It is also frequently volcanically active. The eruptions are small, short-lived explosions, and come from a number of different locations. The same location can erupt again, even after decades. Interestingly, although the activity is centered on Motoyama, the outbursts are rarely there. They seem to follow the edge of the dome. But some eruptions have happened on Motoyama itself, in particular in December 2016 and in late 1969. The larger explosions can leave holes tens of meters deep and wide.

Fumarole activity is widespread, mainly from the crater on Suribachiyama and its steep western slope, and from the northern part of the island. The fumaroles deposit sulphur which was commercially mined until the war. At the top of Motoyama there are even some boiling mud pits. The vents move around, old ones go extinct and new ones appear.

On the map above, from Ueda et al., 2018, the numbered circles indicate the known locations of eruptions since 1890. The most frequently erupting location is ‘1’, with 13 outbursts, and ‘7’ with 10. These two locations are next to each other.

The 12 September 2018 eruption is close to location ‘10’ which previously erupted in 2001. It is a repeat offender.

The map also indicates four seismic stations. One, 0605, is located at Suribachi; the others are at and around Motoyami. They have provided continuous GPS measurements since the late 1990’s. Before that, measurements were taken every two years. Between 1980 and 2000, the GPS data showed relative little change: the rapid changes in the 1950’s and 60’s had given way to a quiet few decades. But after 2000, renewed uplift began to show, and since 2010 it has accelerated further. This was accompanied by increasing earthquake activity. Suribachi remained relatively unaffected, with minor uplift beginning to show only in the last few years. But the movement near Motoyami has been extreme.

Station 0604 has risen by 5.5 meters since 2000, most of which happened after 2011. Not many volcanoes in the world have shown such large movements! This continued from the pre-1980 events: between 1920 and 1980, the maximum uplift on the island was 11 meters. The peak at that time was north and west of Motoyama, while Motoyami itself rose by 6 meters. This time, the uplift seems centred on the south side.

Volcanic activity also accelerated. Over the past 7 years, there have been 20 separate volcanic explosions. During the 7 years before that, there was only a single event, in December 2007. There is more here than meets the eye: there are developments below ground.

Below the water

Iwo Jima forms the top of a strato-volcano. Remove the sea, and a large mountain appears, 2 km tall and 40 km across.

The plots below (from Sohei Kaizuka, 1992, Quaternary International, Vol. 15/16, pp. 7-16, 1992) show the detailed bathymetry, Iwo Jima is surrounded by a smooth under-water plateau at a depth of some 15 meters. At the outer edge of the plateau, there is a drop to a depth of about 100 meters, followed by a patchy rise which in a few places sticks out above the water. Outside of this rim, the mountain steeply falls to the sea floor, 1500-2000 meters below. It is a sizable volcano!

The patchy rim runs roughly from Kaimawa and the island of Kangoku-iwa, around the north side, to Higashi-iwa, 2 kilometers off the east coast. The rim is about 1 km wide. This is wider than Kangoku-iwa: there are four rocks which just break sea level a few hundred meters on the seaward side of the small island, which also are located on this rim. Two of these are visible as white spots on the August 2018 image above, west and northwest of Kangoku-iwa. On the north side, the raised rim is located some 100 meter below sea level. But to the south, the plateau ends with a sharp fall, without a clear raised rim. The profiles shown above have rims at positions A, B, D and F, but there is no indication at positions C and E.

The rim is argued to form a 10-km wide caldera. Iwo Jima and its plateau covers much of the caldera; Motoyama is near the centre. But the classification as a caldera may not be fully certain. The raised rim only extends halfway around the island, with Suribachi placed outside it.

The inner part is unusually shallow for a caldera. But this flat top, 10-km wide, on a mountain 40-km wide, unusual for a volcano, makes sense from the point of view of wave erosion. This has kept removing the top, down to the depth where waves can reach, some 15-20 meters. A caldera would imply a massive explosion removing the entire top of the stratovolcano down to exactly sea level. Erosion can do the same thing, but takes longer.

The rim has had volcanic activity. Kongaku-iwa consists of lava. Higashi-iwa looks like a volcanic cone, similar to Suribachi. Suribachi itself is just outside the rim. But the volcanic outbursts over the past century have been minor crater-forming explosions, rather than cone building, and have taken place on the plateau and the island, and not on the rim. Clearly Iwo Jima can do much more than what we have seen in recent years.

History

In fact, the island has in the past blown its top, and it has done so more than once. The evidence is everywhere. Motoyama is covered by pyroclastic deposits. Suribachi has its own pyroclastic layer, with some lava. Kangoku-iwa consists of lava. Bore holes at Motoyama going 150 meters have found alternating layers of lava and pyroclastic deposits. This adds a warning from history to the on-going inflation. It would be useful to know the full volcanic history of Iwo Jima.

Geological map, Ueda et al. 2018. The map shows the various parts of the island, with the local names. The colours indicate various deposits, including pyroclastics and some lava.

Pyroclastic deposits surround both Motoyama and Suribachi, but they form separate layers and do not come from the same eruption. It appears that Motoyama erupted first. Carbon dating has been done on the lowest layer of ignimbrite and on the rocks of Kaiwama beach. Lava is itself of course not date-able: the carbon is obtained from whatever organism was buried by it. At Kaiwama these were shells, which were dated to 131+-20BC and 31+-20 BC. At Motoyama, interestingly, it was carbonized wood and twigs, dated to 761+-20BC and 762+-20BC. This means that Motoyama, at the time of the major explosion, was partly above water and was forested.

Around 2700 BP, this forested island was destroyed by an explosion. The island disappeared below water, were the ignimbrite rained down. Next, lava came and build up a new dome, but it remained submerged. The lava had an unusual composition called trachyandesitic. More eruptions followed, with layers of pyroclastics. How long this lasted is not known. Based on the carbon dates of the shells, it may have continued for over 500 years. It left a yellow, soft tuff, used in the war to dig shelters.

Suribachi formed afterwards, but how much later is not really known. It existed in the time of Cook, and probably also in 1543, and must therefore have formed earlier. That still leaves us a 2000 year window. Trachytic magma was erupted at Suribachi three times, first as marine pyroclastic eruption, second effusive in shallow water, and finally form a pyroclastic cone on land.

Now the third phase started, where Motoyama calmed down but inflated, at an average rate of 20 centimeter per year. Precisely when the inflation started is not known. At has lasted at least 1000 years, but may also have begun shortly after the Motoyama eruption. And it is still continuing, with frequent volcanic activity. The fact that the top of Motoyama is littered with old coral shows that there was no lava associated with the rise. It was pushed up from below, not build up from above.

In this history, Motoyama is the sum of the 2700-2100 BP eruptions pushed up by the subsequent inflation. The under-water plateau surrounding the island may be the result of the volcanic ejecta, less affected by inflation and continuously decapitated by the waves. Suribachi is a separate eruption, perhaps 1000 years ago, perhaps older.

What about the caldera rim? If this is a caldera, it existed already before the eruption at 2700 BC. There must have been a massive eruption, but all we can say is that it was earlier than 2700 BC. There is no evidence for this other than the partial ring. However, there is another layer of lava underneath the Motoyama lava, called the Hanareiwa lava, and this shows that there were earlier eruptions. The age is unknown.

Seismology indicates that below the Hanareiwa lava is another lava layer. Together, the three layers are 200 meters thick. Between 200 and 500 meter deep is a high velocity layer, presumed to be tuff. This must be from an even older eruption and perhaps this was the caldera forming eruption. Below this is even more lava.

Pyroclastics in a Motoyama cliff face, surrounding a large tuffaceous block

Magma on the move

But what is causing this extreme, long lasting inflation? Intermittent inflation and deflation in large calderas is common, and normally caused by moving hydrothermal water. But the inflation at Iwo Jima is far too large for that. It is caused by accumulating magma. The geodesic measurements show that there are shallow sills underneath Motoyama. They grow, erupt and deflate, pushing the summit of Motoyama up and let it come down again. But at the same time a much larger area is continuing to inflate. That indicates a deeper, and growing, magma reservoir.

And what is causing the eruptions? They are phreatic, meaning caused by water. It appears that there is water inside the deep tuff layer, 200-500 meter under ground. Rising heat brings pockets of this water to the boil, but it can’t get out because of the seal of solid lava above. The lava is pushed up but the agitated water, causing rapid inflation and earthquakes at ground level. After a few days a crack develops in the lava seal. Now we get a sudden explosion, as happened on 12 September this year. The eruptions are primarily in the region where the rise of the central region has caused faults, around Motoyama but within the caldera rim. Two such faults became active shortly after the war.

So where is the magma? The shallow sills are thought to be 800 meter to 1 kilometer deep. It is fed from a deeper magma chamber, where the main inflation occurs. A pulse of magma into the deep chambers brings with it heat, which percolates up into the tuff water. Phreatic eruptions follow. Iwo Jima is currently in such a phase.

Future history

In the long term, Iwo Jima seems to repeat itself. The inflation will continue, but eventually a major eruption will break through and destroy the island. Pyroclastics and lava will build a new dome. After a few hundred years, the eruptions cease. Inflation resumes and over time the island reforms. Until the next eruption.

Where are we in the cycle of Iwo Jima? That is not easy to know. However, it is unlikely that the island was much larger than it is now, at the time of the 2700 BC eruption. The build up to the next one is well under way. But when exactly is impossible to say. How large would the eruption be? We can make a maximum guess by assuming that a 100 meter high island, 23 km2 in size, is replaced by a 200-meter deep hole. That suggest something in the range 5-10 km3. This the DRE value: the tephra will be several times larger. At the top end, a Krakatoa-size eruption might be possible.

But volcanoes do not like being predictable. Sometime before 2700 BP, perhaps long before, it may have done a significantly larger eruption. Just to keep us on our toes.

Iwo Jima has played a part in shaping the post war world. The memories of that event run deep and have left scars, but scars are also signs of healing. We should not forget what happened here, but it belongs in the past. While Iwo Jima keeps rising, the volcanic heritage will become more and more important. One day, it will happen again.

Albert, October 2018

Recent papers on Iwo Jima, extensively used for this post:

Volcanic History of Ogasawara Ioto(Iwo-jima), Izu-Bonin Arc, Japan Masashi Nagai* and Tetsuo Kobayashi, 2015, Journal of Geography(Chigaku Zasshi), 124, 65–99 (with many images of rocks formations on the island)

Phreatic eruptions and deformationof Ioto Island (Iwo-jima), Japan, triggered by deep magma injection, Hideki Ueda*, Masashi Nagai and Toshikazu Tanada, 2018, Earth, Planets and Space, 70, 38

source: Nagai and Kobayashi, 2015

Appendix: The discovery of Iwo Jima

In 1542, Ruy Lo´pez de Villalobos sailed a Spanish expedition from Mexico to the Philippines. After arrival, and meeting a mixed reception from the locals, Bernardo De La Torre was tasked to find a route back, taking one ship from the six of the expedition: San Juan de Letra´n, in order to ask for reinforcements. This task failed: the first successful eastward crossing of the Pacific happened only in 1565. De La Torre sailed a route roughly north/northeast, reaching 30 degree north and finding a number of new islands, but eventually was forced back by storm and lack of water. The chronicles of his journey appear to be lost, but the trip is mentioned in several documents from the 1540’s and 1550’s. These reports are second-hand and in some places are contradictory. The most likely actual journey was pieced together by Bernhard Welsch, in 2004, and I am following his arguments here.

De La Torre departed from the central Philippines on 26 August 1543 (the dates in use at that time were the Julian calendar. The Gregorian calendar was not adopted until 1582). He sailed east for a few days before turning north, eventually crossing the tropic of cancer. (Typically, reported latitudes are reliable, but longitude could not yet be measured.) Several islands and groups of islands were discovered on this leg, before he was forced to turn back.

On 25 September 1543 they sighted a small island at 26°N which they called Mal abrigo (bad anchorage) because the sea was breaking against it. They sighted two more islands 26 leagues further which they called Duas yrmaas (Las dos hermanas, meaning The two sisters), but didn’t land there. (A spanish nautical league at this time was not perfectly defined, but in practice there were about 15 leagues to a degree, so 26 leagues was a bit less than 2 degrees.) Later they saw three (one of the reports says four) more islands, at 24 and 25°N. One of these was volcanic with fire in three places. These islands were called Balcones (Volcanoes).

On 2 October 1543, they sighted an island they called Forfana (the orphan), beyond which there was a high mountain or rock, with fire at five places. But the story here appears confused, because the description ‘fire at five places’ sound very similar to the previous ‘fire at three places’. The first is reported in one of the second-hand sources, and the second in another. It seems likely the two sources were reporting the same observation, but attributed this to different islands. In reality, only one active volcano was seen.

On 18 October 1543, between 29° and 30°N, after hitting a northerly storm, they became worried about their supply of drinking water. They turned around and after 13 days arrived back at the departure point. On the way back, they came across some smaller islands ranging in a north–south direction from the 15th to the 16th degree N latitude, which were the Ladrones (the Marianas), but they did not anchor there.

So which islands did they find? The first ones, Mal abrigo and Los Dos Hermanos, are accepted to be the Daito islands. Mal abrigo appears to be Oki Daito, 24.5°N and surrounded by coral reefs, and the two sisters are Minami-Daito and Kita Daito, about 1.5 degree due north of Oki Daito and less than 10 km apart. One of the old but second-hand reports places the first island at 16°N, and this is therefore often identified with Farallon, but this appears unlikely: the Daito islands, 10 degrees further north, fit much better with the descriptions.

The three ‘Volcano’ islands are identified with the Kazan Retto group, 10 degrees due east of the Daito islands; Iwo Jima is the middle one of the three islands of this group, and it is located at 24.8°N. That identification was first suggested in 1803 by Burney, a member of the Cook expedition. Burney wrote :

‘it will appear very probable, that the Sulphur Island, with the North and South Islands, seen by the Resolution in her return from the last voyage of Captain Cook, are the islands which were called the Volcanes, discovered by the San Juan. Their agreement in number, their spreading nearly a degree in latitude, and in the same parallels, and their appearance so well corresponding to the name, form a combination of circumstances that amount to very little short of conviction.’

The next island that was discovered was called ‘Forfana’, and is said to be an uninhabited island 30 leagues (150-200 km) from ‘Volcanes’. It was sighted on 2 October 1543. The direction is somewhat problematic. One source says it was east to northeast from the Volcanes, where only empty ocean exists. But this source also states that the second Daito island discovered is northeast of the first, while in reality it lies due north. If the same mistake was made here, the final island really lies in a north-northeasterly direction. And there are islands there: the southernmost part of the Osagawara archipelago, where the nearest island is 150 km from the Volcano Islands. This makes ‘Forfana’ to be Hahajima, the southernmost of the major islands, or one of the small islands which surround it at 2-3 km away. This fits well with the description of an ‘orphan’ (Forfana) beyond which was a high mountain. The highest mountain on Hahajima is over 400 meters.

The route from the Daito islands to Iwo Jima and on to Hahjima is not straight. It runs a bit south, and turns northward. If De la Torre passed through the Iwo Jima groups east-west, he could well have missed either the southern or northern island of the group. If Iwo Jima consisted of two separate islands at the time, as seems likely, it is perhaps possible that of the three Volcano islands he saw, Iwo Jima accounted for two. But this is speculative and mainly illustrates the uncertainties around the story.

After Hahajima, De La Torre sailed on for two more weeks into the open ocean, but eventually was forced to turn around, found Vila Lobos gone, and finally met up with the expedition around the Moluccas (not far from Sulawesi) in early 1544.

There are some lessons from this story. The San Juan was nowhere near where the sailors thought it was. It sailed a complex route, first east, than due north, east-southeast again, and finally north-northeast, putting the ship far to the west of where it though it was going. If you can’t measure longitude, the course can be a bit of a guess. Some of the deviations can be explained by tacking against a predominantly northeasterly wind, and others by the effect of the west-flowing north equatorial current, which becomes the northeast-flowing Kuroshio current in the region of the journey of De La Torre. Some may have been deliberate. He may have been aiming to catch the returning North Pacific current across the Pacific, at 30N, and therefore trying to gain latitude before turning east. Or he may have been deliberately looking for islands, in order to obtain water. We can only guess.

We have further learned that Iwo Jima was discovered after 25 Sept but before 2 Oct 1543 (Julian dates). Often, the first date is given, but that is for the Daito Islands. Looking at the distances involved, the most likely discovery date is 30 September 1543. We have found that the name ‘Sulphur Island’ comes from the Cook expedition: De La Torre’s name for the islands was just ‘Volcanes’. What we do not know is what Iwo Jima looked like, however as it was clearly labeled as ‘volcano’, the peak of Suribachi must have existed, as this is the only obvious volcanic feature seen from a distance.

That fire-belching volcano

There is one final point to solve. What was that erupting volcano that so impressed the sailors that two second-hand accounts tell the story, albeit attributed to different islands? One account places it at the Forfana group, i.e. the eruption was at or near Hahajima. This group of islands is indeed of volcanic origin, but far from recent. The eruptions were several million years ago, the chain has gone quiet and the eruptions are nowadays at a separate chain of islands further west, where for instance Nishinoshima is located. In spite of the statement placing ‘a high mountain or rock, which was belching forth fire at five places‘ at Forfana, this event cannot have been here.

The other account places it at the Volcano islands: ‘‘they sighted three more islands; one being a volcano belching fire at three places’. This narrows it down to one of three possible islands. Assuming both accounts are for the same event, we are looking for a high mountain with multiple eruption sites.

The three Volcano islands are, from north to south, North Iwo Jima (Kita-ioto), Iwo Jima (Ioto), and South Iwo Jima (Minami-ioto): together they make up the Kazan Retto group. The southern island is a single, 900-meter tall cone, about 2-km wide at sea level. There was a marine eruption a few kilometers off the coast in 2005, where lava floated to the surface. The northern island, Kita-ioto is larger but slightly less tall, at 800 meters: it appears more eroded. The summit of Kita-ioto is extinct, but there have been several eruptions off the coast over the past two centuries. Neither island is known to have had historical activity on the main mountain on-land. But the description clearly refers to an eruption on land. Although neither can be excluded, given that Iwo Jima itself is known to erupt on-land, it is a likely candidate for the erupting mountain.

But Iwo Jima also shows little or no evidence for recent lava. The most recent ‘fire’ eruption was probably the one which caused the top pyroclastic layer around Suribachiyama, and this could be as young as 1543. But the description gives no mention of explosive activity, just multiple fires. Phraetomagmatic explosions, similar to the current activity, can also be excluded, because it lacks associated light. Was the entire description made up, or greatly overstated?

There is an alternative. The crater of Suribachiyama, and other places on Iwo Jima, can show heavy fumarole activity. Looking at the dates and distances, De La Torre probably passed here around 30 September. Two days later, Oct 2 1543, was a full moon. Did he perhaps pass at night, and see very active fumaroles reflecting the light of the nearly full moon? That might have looked like fire to people unfamiliar with fumaroles, and it would explain the multiple locations where fire was seen. A night vision could even explain the confused reports about the actual location of the event.

So, event though the circumstances of its discovery are now clarified, the volcanic fire that so impressed the sailors remains a mystery. If only we could recover the lost chronicles of the discovery! Second-hand reports, even from within a few years of the events, leave too much unclear.

Main source: (2004) Was Marcus Island discovered by Bernardo de la Torre in 1543?, The
Journal of Pacific History, 39:1, 109-122, DOI: 10.1080/00223340410001684886

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344 thoughts on “Iwo Jima in 45 eruptions”

  1. https://volcanoes.usgs.gov/observatories/hvo/hvo_volcano_watch.html

    Something noteworthy, kilauea has a below average fluoride concentration for a basaltic volcano, but the sulfur content of the magma is the highest anywhere on earth, even more than Iceland. That would make sense with what HVO was saying about fissure 8 erupting the highest SO2 flux of any observed basaltic eruption in recorded history.

    I guess when you consider how long there was a steady 3000-5000 tons of SO2 daily (12,901 days) then there was about 55 million tons of SO2 from kilauea during pu’u o’o, or about 1.5 million tons a year. There was then bout 4.5 million tons from the leilani eruption, so leilani was equivalent to about 4-5 years of pu’u o’o in 3 months. By comparison holuhraun erupted 11 million tons in 6 months. I guess this shows that leilani and holuhraun were about the same intensity, holuhraun was twice as long and correspondingly had about twice as much SO2. It might have been somewhat less than twice as big in overall volume though, as I dont think the thickness of the lava in the kapoho and ahalanui areas has been taken into account (300 meters thick at the new coast) and that adds a lot (about 0.2 km3 from a rough calculation).

  2. hehehe…. Now give me 100 million km3 in 500 thousand years…
    Unleash the magmageddon… unleash it
    The bigger the flood basalts are… the happier I gets
    Be happy I cannot controll earths volcanism
    When it comes to volcanoes… Im superbad

    • I think you probably mean 100 billion 😉
      100 million is only 2 pu’u o’os.

      Anyway if you want flood basalts, Hawaii has the volume to age ratio of a pretty big flood basalt, it just doesn’t have 1000 km3 individual lava flows. However lava flows as big as 100 km3 erupted north of the islands in the submarine north arch volcanics, analysis found the magma to be full of bubbles and that it was likely erupted rapidly like a flood basalt proper, all of this is in the last half million years and probably still ongoing if also infrequent, likely there is several thousand km3 of lava erupted down there.
      This year also proves that at least kilauea is capable of holuhraun scale eruptions without being incapacitated, something even most Icelandic volcanoes can’t do including the one which actually created holuhraun…

      The Hawaii hotspot has erupted about 600,000 km3 of lava in the past 2 million years, first as Maui Nui and then as Hawai’i, and about 150,000 of that is in kilauea and mauna loa on their own, mostly in the past 300,000 years or so. The columbia river basalts – a ‘true’ flood basalt – erupted maybe 200,000 km3 in 3 million years, 1/5 of the rate of Hawaii, it just decided to do it very episodically and so the flows were individually very big.

      • “incapacitated” → The jury is still out on that one.

        • It is still feeding lava into the east rift. That is not where it would be expected to go after an eruption like this year and the drain of magma it caused. The inflation near heiheiahulu is not insignificant, it has reached over 10 cm in only about 2 months, comparable to pu’u o’o before all this happened.

    • That was the boat store / shed, I believe. Expensive….

      • I think “A” boat store / shed is better phrasing. The mess down there it pretty extensive.

        For all; the significance of it being a boat shed is that one end of the structure is usually open and allows wind to get up inside of the building.

        From my many trips down into this area, I think the region of the video is along Star Ave going into eastern Callaway from the North, down past Bay County Jail and Tram Rd. (Tram Rd being the route to a State VA nursing home in the area)

  5. Kilauea’s East Rift Zone Chain of Craters around 1964-66 before Mauna Ulu:

  7. Anyone have an idea where this is at? It’s from a screen cap of the movie “Frost” so it’s pretty likely somewhere in Iceland. I’m mainly interested in what mountain that is in the background. The context of the movie is that two people get into problems up on the glacier, and I don’t know if it’s Mýrdalsjökull or Vatnajökull they are inferring for a setting. The version I’m watching is subtitled in English, but occasionally the meanings of the expletives are quite clear without translation. 😀

    • It’s not a “bad” movie, but the ending does leave you hanging.

      That the title card appears just before the movie ends is an interesting touch.

      • i’ve seen enough snow… and frost and ice…and dark…. really going to miss this one… but the pillers are quite high so must have large tide. Can’t be eastern Canada?? Must be Iceland?

        • Well, yeah, but where in Iceland? It’s an honest question, I’m curious.

          (BTW, astute observation about the tidal range)

          As for the movie, much of it was spend with the two main characters trudging around in the driving snow on top of a glacier yelling “Hello?”

        • And I really would have liked a connection about what exactly was going on. It’s one thing to let your audience fill in the back story, quite another to leave the central premise hanging. I think that’s why Steven King stories are so bad. He spends all his time on character development and then haphazardly cobbles sn ending together… but at least it’s an ending.

        • The part that throws me is the placement of the moon. That implies a view pointing mostly east or west.

        • Note the sun (moon?). It is obviously winter so the sun must be low in the southern sky. The boats are north of the mountain. That rules out most of Iceland’s glaciers which are on the south coast. Why are the boats in the water? In a freezing climate, they would normally be on dry land for the winter.

    • If it is the 2012 one about physiologist Agla and filmmaker Gunnar waking up to find their camp abandoned, the movie was filmed in Iceland on Langjokull Glacier. As for the harbour, Akureyri Husavik? Husavik faces east and has similar mountains.

      Two pictures here (How do you embed them in a post on this site?)
      https://postimg.cc/gallery/14pnvlllk/

      • Yep, that’s the movie. I got a kick out of it just from looking at the terrain.

        Some of those scenes just didn’t mesh well with the story. The parachute flare visible over the guys right shoulder before any one in the movie had fired one confused me. And I nearly choked when it appeared that she had administered defibrillation while her companion was still performing CPR. I thought for sure that the next scene was her dragging his body and not the other guy.

  8. Gjalp in grimsvötn 1996 was pretty impressive
    700 million cubic meters of subglaical lava was emplaced under a week.
    plus a good ammount of ash and tephra. The total erupted volume of that is likley close to 1km3
    I wonder what the eruptive rates was the first days… huge.
    It was in a way grimsvötn 2011 but a little slower

    • 100 million m3 a day, about 8 times the average for fissure 8, or about 1000 m3 a second. Basically holuhraun on its first day but subglacial. It would have been an impressive lava flow if on dry land, probably about as big as holuhraun in area but not as thick.
      Still rather a lot less than grimsvotn 2011, or skaftar fires, both of those were around 10,000 m3/s which is probably beyond the threshold for the basalt being pulverised by the force of the blast – these eruptions would have been plinian whether the glacier was there or not.

      Basaltic plinian eruptions might be the most potentially hazardous eruptions, they are surprisingly common but seem to be assumed to be impossible even with at least 3 in the past 100 years. Grimsvotn is far from anywhere so it was fairly safe but a plinian eruption from kilauea would be a very different story although one that HVO is aware of at least. I don’t think we even need to go into what could happen if etna erupted in that manner with its over 1 million inhabitants…

      • In fact every plinian eruption is dangerous, but why would a basaltic plinian eruption be more dangerous than the more usual andesitic, dacitic or rhyolitic ones?

        • Why would a Plinian basaltic eruption be more dangerous? Simple. People wouldn’t be expecting it.

          People living near volcanoes such as Taal or Ranier or Vesuvius know that when it erupts it can go bang in a big way. They may choose to ignore that knowledge, but they have it. People living near volcanoes such as Kilauea or the Icelandic basaltic volcanoes don’t realise that such a thing as a Plinian basaltic eruption exists: their conception of those volcanoes is that at worst they can do something like Holurahn or Leilani Estates. In other words the vast majority of the time you have enough warning to get out of the way of the eruptive products and even the gases can be avoided or mitigated in a lot of cases.

          They have no experience of a really, really big basaltic eruption like Laki. There are no photos of Laki. There is no film of Laki. The most we have are descriptions from the few witnesses and some paintings. Photos and film make an enormous difference to the immediacy of an event: look at the reaction They Shall Not Grow Old from Peter Jackson has garnered. The main thing he has done with that is taken WWI footage, slowed it down to the correct frame rate, cleaned up the scratches etc on the film, and then done a very good job of colourising it whilst adding some foley sound, dubbing some of what lip readers determined the soldiers were saying when filmed and put some recordings of veterans from the 1960s into the documentary. It has an enormously higher impact than the original, untouched footage. Conversely WWI battles are much, much more immediate to us now than the Battle of Waterloo was a century ago. We are now at the same distance from the battles of 1915 as they were from the Battle of Waterloo when WWI ended. The last WWI veteran in the UK died less than 10 years ago. Due to lower lifespans the last Waterloo veteran died after a bit less time in 1898. Nevertheless at the 100th anniversary the vast majority of people would have had a decent chance of knowing someone who was around at the time. We can see footage of the events and photographs of the events. Even the US Civil War is much more immediate than events only 15 to 20 years earlier because of the number of photographs associated with it.

          We have footage of a very big non-basaltic Plinian eruption at Pinatubo in 1991. Far from the size of Tambora of course, but still pretty large. We have photographs of the Valley of Ten Thousand Smokes after Novarupta. We have nothing comparable for a really big basaltic eruption.

          • Some of kilauea’s prehistoric eruptions had pyroclastic flows that went as far as 20 km from the summit, the tephra is exposed in some of the chain of craters. The 1790 event, just like skaftar fires, is a deceptively recent event that was not actually recorded in any way, except second hand reports from people who saw it as children. The situation now is very similar to the conditions that existed before that eruption, and yet 10000+ people are generally wandering around within the danger zone at a given time, probably more now. The danger zone is way bigger than you would expect too, it includes Volcano, most of the chain of craters, in an extreme but not impossible case it could include Pahala and much of the subdivisions east of kilauea. Explosive eruptions could also happen in the lowest part of the rift, kapoho crater is proof, 1960 is observed.

            Even more than hypothetical scenarios, look at what happened on fuego earlier this year…

          • Also I would say that some of etnas lava fountains would be a good approximation to the initial stages of the skaftar fires. The only difference is that there were no lava flows on Etna with these eruptions. Izu oshima in 1986 also, 1600 meter lava fountains along a fissure, though again with fairly small lava flows.

            Holuhraun and Leilani could be seen as the large VEI 6 of basaltic volcanism, comparable to pinatubo and krakatoa, skaftar fires is somewhere in the upper VEI 7 almost a supervolcano range, one of the most powerful eruptions in the Holocene epoch. The energy of that much lava cooling to room temperature is enough to pulverise 600 km3 of Rock to ash, no explosive eruption in the Holocene has reached this point, or even come close, and they definitely aren’t every few hundred years either. Really the only thing more energetic than a big basalt eruption is a big (1km+) asteroid impact, but those make VEI 7s look common.

          • If you want to take a look at a subplinian basaltic eruption: 2015 paroxysms of etna’s main crater. 1400m high Lava fountain, total eruption column 8km. I watched it live in total awe.

  9. Still .. I wants my asteorid in Grimsvötn 😏😏😏😏😏😏 433 Eros woud be a good projectile to launch into Grimsfjall

      • It woud be so fun
        Pieces of Hekla and Katla ends up on the moon… and impact vaporize down into the Very plume head
        Weeks after you haves huge flood basalts

        • This particular asteroid would create a crater about 300 km across. You’d lose rather more than Hekla and Katla. It is also bigger than chicxulub. No warm blooded animal bigger than a cat would survive. It would be dinosaur deja-vu.

          • Just Imagine that plume of rock vapour rising from Iceland after impact
            25 000 C or something like that!

            Up in space the rock vapour and blown up remains and ejecta,
            Cools into zillions of tiny glass droplets that Then reenters the atmosphere as a global firestorm

      • The first second of impact is like placing a small B class star on Earth!
        Dinosaur event was 20 000 C at first impact contact

        Intensely bright
        The rock vapour plume expands as it cools and more materials are vaporized as it burrows down
        Thermal radiation will be felt in Norway, Greenland, Faroe islands and Ireland and scotland .. brutal

      • I wants it right at Grimsfjall
        Maybe in the caldera.. but otherwise I direct hit at Grimsfjall or Skaftarkatlar
        433 Eros woud be an excellent projectile

      • Those numbers are wrong. The crater size comes out as 3 km which is much less than the size of the asteroid – not possible. You put in a density of 2.8kg/m3. That is about the density of air. The correct value is 1000 times higher.

        • Just using what the fallible tome gives me.

          Wikipedia

          I re-ran it on their new interface (allegedly with the same formulas) and used a density from the drop down of “porus rock” (1500 kg/m³) and it gave me;

          Transient Crater Diameter: 75.8 km ( = 47.1 miles )
          Transient Crater Depth: 26.8 km ( = 16.6 miles )
          Final Crater Diameter: 134 km ( = 83.1 miles )
          Final Crater Depth: 1.29 km ( = 0.802 miles )
          The crater formed is a complex crater.
          The volume of the target melted or vaporized is 3380 km^3 ( = 811 miles^3 )
          Roughly half the melt remains in the crater, where its average thickness is 749 meters ( = 2460 feet )          .

          Seems to be deep enough to incorporate most of the magma chambers into the destruction. Within 500 km of the impact, you’re gonna have a really bad day before any thing from the strike gets to you. You’ll be laying there writhing in pain when the shock front gets to you.

          Time for maximum radiation: 9.57 seconds after impact
          Visible fireball radius: 143 km ( = 88.8 miles )
          The fireball appears 65 times larger than the sun
          Thermal Exposure: 8.69 x 10^8 Joules/m^2
          Duration of Irradiation: 35.2 minutes
          Radiant flux (relative to the sun): 411

          Effects of Thermal Radiation:
          Clothing ignites.
          Much of the body suffers third degree burns.
          Newspaper ignites.
          Plywood flames.
          Deciduous trees ignite.
          Grass ignites.

          • That’s very close to the Vredefort Dome impact crater in SouthAfrica, one of the largest in the world and is visible one Google Maps for those interrested.

  10. Some photos of Heklas 2000
    Lava flows, just before eruption stopped

    • But this particular image can’t be from an in-land glacier.

      • I don’t think that’s a glacier at all, just a snow dusted mountain. The best match I can find on Gurgle Urt is the harbour at Ólafsvík on the Snæfellsnes peninsula.

        • yes, that is very plausible. It has that harbour wall, Not sure about the mountain but presumably this was a tele-lens.

      • Another possible location would be somewhere in the eastern fjords but in those mountains the horizontal basaltic flows are easily visible and are usually flat topped.

  12. This was Hekla .. just before it stopped puking lava in 2000, slow and viscous it emerges
    Likley a cool basalt or basaltic andesite
    Slow and steady and viscous.
    Aa lava and even close to the vent its likley extremely stiff to poke

  14. And this shows the last gasps of Holhuraun in 2015.
    Just before the dyke shut off. Little lava pond splashing before it runned dry

  15. Poor Holhuraun… it runned dry.
    In total 1,6km3 of lava was burped out. thats 1600 million cubic meters.
    One of the largest basaltic lava flows photographed
    Still Puu Oo was the largest in recent times, but Puu Oo was mostly very slow

  17. just slightly ot but i’ve observed the moon up here in Alaska and it can be anywhere from any crazy place in the sky….. i’ve seen it from NNE to NNW and including just above the southern horizon… but never high over head. ….. One cannot tell direction up here with the sun or moon…. Better luck with the north star…. i have seen the sun go down just about north…. but then it get’s righ back up again…;) Best!motsfo and don’t forget that freezing water depends on salt amount…..

    • Yep Motsfo, I took a picture of the full moon with McKinley ‘From the Co-pilot’s side
      of a DC-7 Never got high in the sky…. but neither did the sun…
      Just getting a clear shot of McKinley was due to an act of divine providence…

      • yeah, that’s rare… i tell people who go to McKinley (we call it Denali) “Take a good look from the Inlet in Anchorage…. it’s Your best chance.” 😉 Best!motsfo side note: were You coming from Fairbanks? and that reminds me of a way off topic… my favorite quote…………………… If God is Your Co-Pilot….. You’re in the wrong seat. 😉

        • Yep i was flying out of Fairbanks. Prefer Denali too…
          One of my favorite sayings is “God is my Co-pilot but Murphy is the flight engineer..”

  18. “clock ticking” when will Katla erupt….
    I hopes for a large basaltic plinian or an Eldgja sized bleed
    Or a thjorsahraun sized one.. sent into the atlantic ocean
    Im tired of waiting… so tired…. I wants action now! now!

    I wants an eruption! I wants an eruption! I wants an eruption! I wants an eruption! I wants an eruption!
    I wants an eruption! I wants an eruption! I wants an eruption! I wants an eruption! I wants an eruption!

    • So you want something like what happened with Laki then do you? Do you want 20,000 people dead? That is the estimate of the excess mortality thanks to Laki. Please think through what you are saying before you say it: that way you won’t end up advocating for something that will kill tens of thousands of people.

  19. LoL i wants a show safely… Let us have Laki near bardarbunga… where none can get harmed
    Its just me… wanting a show. A new surtsey woud be even a larger thrill

    • To rerun an old VC New Year’s Eve offering:

      A new year alights on a changeable Earth
      We wait in the hope of a volcanic birth
      Rumours of unrest on expectant hearts
      The impatient patience of the watchful guards

      Octopus alike, Bardarbunga sits
      Tentacles spread in its dykes and its rifts
      Feeling for weakness through cracks in the crust
      Sundering rocks which we thought were robust

      Solfatara still sheds its sulphuric smells
      Yellowstone quietly geyses its wells
      Mauna Loa inflates while hiding its threats
      Stromboli’s lava still spurts pirouettes

      Fissures erupting to make people follow
      Flocking to glimpse the jets from the hollow
      But when the flow wanes, away the crowds leap
      In quiet the Earth can return to its sleep

      The future lies hidden in rocks deep below
      Where magma is trying to make fractures grow
      Mantle plumes rising and plates pulled apart
      The Earth in its silence still playing its part

      In faraway places the sleep is disturbed
      where ground is inflating and mountains perturbed
      Shaking begins – the magma is rising
      The world like a phoenix awaits fire’s baptising

      Tremors foretell of the burnings to come
      Delights to the watchers but sufferings for some
      Their houses on fire and lands overrun
      The people are fleeing whilst others have fun

      A new year alights on a changeable Earth
      We hope and we fear a volcanic birth
      Rumours of unrest bring fright to our hearts
      What power the Earth on our lives can impart!

      • OO! Like This! i missed it the first time… Christmas to January 10 is real busy for me… seldom have time to see stuff then … Glad You ran this now…. Best!motsfo

      • Albert – a classic, thank you! You ought to consider publishing these wonderful poems as a collection! Perhaps a Volcano Cafe production? I am in awe of your writing, science and VC inputs. I wish I had a tenth of your abilities. Meanwhile, here’s my bit of doggerel in praise of your wonderful contributions…

        (Please kneel to be sick…)

        There is a great a poet named Albert
        Of many scientifical abilities
        A scene, a science, he can easily convert
        To lines of perceptive poetries

        His knowledge covers mountain to desert
        And the realms of distant astronomies
        With volcanic authority he can often assert
        How magma and plates form the seven seas

        So let us celebrate and raise a glass
        To Albert the poet, the Cafe guru
        His wisdom passed to his volcanic class
        Here in this blog and beyond – to you.

        Well, sorry. I’m no poet but I do want to say how we enjoy your fascinating poems.

    • Skaftar fires was in an uninhabited area, an eruption on that scale isn’t restricted to its local area. Anyway bardarbunga already did its big thing for this past few hundred years, holuhraun was as big of not bigger than most of the veidivotn events when DRE is used. 1477 is still bigger but not significantly so.
      Skaftar fires was a whole different kettle of fish to anything bardarbunga has done since the early Holocene, if you remove thorsjahraun as an outlier, skaftar fires is bigger than all the other veidivotn eruptions put together. The energy release of any of these flood lavas is on par with the eruption that created long valley caldera, and way bigger than kikai – the biggest Holocene explosive eruption. Even using the conventional VEI scale it was at least a large VEI 5 just from its initial vent clearing stage, these people must have watched as a massive line of plinian eruption columns changed gradually to 2 km high jets of glowing yellow-white hot lava, then within days the lava is on the coastal plain with them.

      The eruption that created the roza flow 16 million years ago must have been similar but orders of magnitude larger, the opening phase could have been a VEI 7 in its own right with all the associated features, and then the lava floods out after that maybe for years at rates that are still way higher than observed basaltic effusive eruptions, the cones created could have been like mountains, sentinels to this great eruption long after the lava has grown over.

  20. A New Surtsey woud be superfun
    its so sad… surtsey happened in 1963 instead of 2010 s

    • Surtsey in the 2010s = nishinoshima

      Maybe not quite the same or as impressive of an eruption but nishinoshima is probably going to have more of a future than surtsey, it will likely become a new larger island while surtsey erodes to a plug.

      • Nishinoshima was basaltic andesite and strombolian and viscous flow lobes

        Surtsey was a rather hot Alkaline basalt with fluid Hawaiian activity with lava lakes and tubes

  21. Volcano Party
    Sierra Negras 2005 eruption had giant fountains!

    • Interesting, its a bit off with the dates though but it is also over 50 years old so that is probably acceptable.

  24. Looking at the location of the JOKA station, it is on the north side of heiheiahulu, very close to the main vent of the 1961 eruption and where the june 27 flow exited the rift zone. It is being pushed north slightly, which means that the magma underground is south of the station, or basically directly under heiheiahulu. This is where I think there is a magma chamber, not as big as the ones uprift or under the summit but there must be some magma storage here after having two shield eruptions from this same spot. Maybe there will be a 3rd in the near future, . Depending on the location of the shield, whether it is on the north or south side of heiheiahulu this could be either a boom for tourism if it flows south or it could be a disaster if it flows north to pahoa or east over the entire area. I guess if it is big then all of those will probably happen, but nothing has happened yet so all we can do is watch and wait.

    The problem with having a shield in general this that in the long run is that it is very likely the only way an eruption will end is with another terminator event, very likely almost a repeat of this year and so things look grim for lower puna right now. A while ago Albert said that maybe almost none of lower puna will be left untouched by the lava, maybe that is true and it will just take a bit longer.

    • The northward motion seems to have ended in the past few days. There was also a slight westward drift so the source was not exactly south of JOKA

    • With the area between the LERZ and the MERZ reinflating things do look grim for Lower Puna, after taking a fast look to a topographic map there are several small towns that could be affected by eruptions taking place in the upper part of the LERZ, mainly Pahoa, Nanawale Estates, the surviving Leilani and the Keauohana-Kehena-Keekee Homesteads. The eruption of this year failed to be a terminator event like 1790 and close a period of ERZ activity, there is also an important amount of magma still stored in the South Caldera Reservoir and UERZ so the potential for a big terminator event in the close future is there. There is also the posibility of the ERZ opening a sustained vent there or maybe a series of small eruptions, at least one of the two would probably precede the final event. There is also a chance that the terminator eruption will happen in the upper end of the Puna Ridge, offshore.

      • I don’t think the northward movement has completely stopped, it has slowed slightly though. If the station is also going west slightly then the main source of inflation is in that direction, just east of heiheiahulu, possibly one of the less desirable places an eruption could occur as it has a wider reach.

        The puna ridge is interesting, even only a few km off the coast it is hundreds of meters deep, there seems to be some mechanism which prevents eruptions from happening offshore or with any real size. There is a report of a small event in 1884, and sources seem to confirm it actually happened, but this was probably a local process with no summit influence and it only lasted about a day. In 1960 there were many very small vents trending east from kapoho cone with one of them some distance offshore, these are mostly buried by lava from the main vent and the face the main vent stayed on land shows that it might actually not be favourable to erupt underwater, maybe the inward pressure of the entire ridge is high and so it is easier for magma to erupt in lower puna despite the higher elevation.

        At the start of this year there was a sizable depression in the rift where the lower part of Leilani was. That depression was exactly where this years eruption happened. There is now more of a depression in the northwest part of Leilani, and there is also a rather big gap in historical activity there and going west to heiheiahulu, and the upper part of this gap is exactly where the inflation is occurring now… Not to be a portend of doom but this just can’t end well.

  25. This was Surtseys lava lake in 1964. The lava lake above the vent was there for 13 months.
    It had huge dome fountains and waves rolling over it
    The lava lake feed lava tubes and overflows expanding the surtsey island.

  27. Here is another shot, of Surtseys lava lake when it was going.
    it was quite large 80 meters across, sometimes it overflowed all over flooding the entire south island.

    • With a nice hard coat of armor to protect from the wave erosion…

  28. Nice film of Surtsey, shoter version of “Land Out Of The Ocean”
    This was a time when my mother was just a tiny child, but my dad who is 66 remebers
    Surtsey very well indeed as a child. These are likley the only moving images of Jolir and Syrtlingur in action.
    This is in a way Holhurauns volume erupted underwater, but somewhat slower.
    Surtsey in first days likley had eruptive rates of 100 s of cubic meters a second, then it slowed down alot.
    Last activity was seen in 1967 I think.

  30. A category-5 hurricane is heading for western Mexico. Not a densely populated area but probably not well prepared either

  31. when the tropical cyclones, gets tiny pinhole eyes.. its when they are most intense
    Such a tiny 5km wide pinhole eye as Wilma ( 2005 ) had is very much like an oversized tornado in windspeed and how it behaves. Patricia had similar specs and windspeeds well over 300 kilometers an hour
    Terrfying! its like a strong F3 or weak F4 on a … huge area
    these storms are the most destructive of all storms.

    • Dunno… that’s far smaller than Camille was in ’69.

  33. What an amazing possible future for Willa…and if the FV3 experimental model pans out, we’re gonna be talking about this one for a while. ATTM, the forecast has it tracking NE off the Pacific and pummeling the Mexican coast/NMexico before tracking into southern Texas then east along most/all of the Gulf Coast. As Willa’s remnant low continues east, it will track right over the hardest hit areas near Michael and the Florida Panhandle before shifting NE to pay the Florence folks a visit. Once Willa hits water again, somewhere near the Outter Banks, the storm will re-intensify and continue out into the Atlantic, however a sizable piece of energy…possibly the core low… will transistion into what looks like a pseudo N’easter as it begins to tracks NE along the Atlantic coast. By the 28th/29th, Willa’s remnant/sibling low will be near southern New England before the whole mess starts lifting NE and out of the area.

    So in a nutshell it looks like the entire (and super-soggy) American eastern seaboard, the SE coast, the entire Gulf Coast, and the desert SW from eastern Arizona to west Texas are going to get popped by a EPac hurricane remnant-on-steroids.

    • Dunno. There’s already the makings of a Low near Corpus Christi, Willa seems to drive into that and take over. It’s not uncommon for a storm to sap the energy of a weaker system and use it’s moisture and/or forming structure as it’s own. It’s not often, but not uncommon.

      The cute bit, is that like the S Georgia coast and the area around Jacksonville with Michael, they got a hurricane warning for their coast from a storm coming from the west. S Texas may be getting one from the other direction as well.

      Bad time to be on the road on foot or in a vehicle in Mexico. Dry gulches can get un-dry very quickly.

      • CH & GL,

        OT, but quick comment. I know with the recent hurricanes in the Carolinas, FLA and VA (I live in SE VA and was affected by the last one) that hurricanes/storms have been a topic here. Full disclosure, I am not a meteorologist (though I did stay at a Holiday Inn Express one time), but to combine both your posts, I saw a forecast today that the hurricane will cross Texas into the gulf and combine with the Low developing in the gulf noted by GL, then potentially transitioning into the N’easter noted by CH.

        Back to your regularly scheduled programming… 🙂

        • I can’t disagree with that. What I am waiting for is the backside pull that will draw winter down upon us. We got a bit milder after Michael, but I’m wanting more. When I let the dogs outside I want them to look at me like I’m crazy.

          One oddity that I’m seeing in the patterns, is that the “Azores High” is a bit north and acting as a block to normal storm flow.

          • And that’s funny, we got colder. We’ve had lows in the 40’s and 50’s the last few days and highs in the 50’s and 60’s. Just got used to having the AC off (and saving some money), and my wife turned on the heat this evening (I’m gonna turn it off when she goes to bed).

          • That Atlantic blocking high is going to send an artic blast over us in the UK at the weekend. A rather unusual pattern for this time of year as it’s usually full jet stream storm conveyer belt time. A warmer artic will do that though, a weaker polar vortex (due to reduced temperature contrast) means a meandering jet stream and more warm/cold plunges. If we get snow this weekend on the Moors it’ll be the first time I’ve ever seen snow at this time of year.

        • The hurricane (as a self-sustaining system) itself will have long collapsed by the time it reaches Texas, but remnant moisture and a residual cyclonic flow over the Gulf coast will be drawing in oodles of Gulf moisture that has the potential (IMHO) for setting up some banding/squall lines that can be prodigious rain producers..on the order of several/many inches in a few hours should one of the lines start training over a given slot….and especially not good for water-weary folks in the recent flood areas.
          As Lurk mentions, the backside may be the more important feature as colder air will start working into a really juicy airmass with enough evapotranspiration present to support heavy rains/convection unusually far inland. If the timing is right for the CF coming down from the NW to encounter Willa’s remains, we might be hearing of some severe storms breaking out all along ex-Willa’s path….and maybe even a tornado given the steering jet will be overhead, with decent low level sheer to enhance rotation.

          • Well, tornadoes are something the SE US is good at. We always have em spinning up along advancing fronts. The good part is that ours don’t typically get to the size of the Kansas monsters. They grow unstable and peter out just as quickly as they form… but they can still rearrange your furniture.

  34. https://www.facebook.com/john.stallman.9/videos/1364058890396291/?__tn__=%2CdlCH-R-R&eid=ARC3t6dj_h7iShnvolU6SrmehkZ4TU5dJm0T910lcRN4JgG7gel4m7rxv3hM9_UW-_l9ReFaHWQCtOQz&hc_ref=ARRL77AsqB5nTgNz8TIo24e0FFc78TI4xGUBYk7TOAUom97uZSswU0qslwv4KIKU0Lo&hc_location=group

    There is also this from yesterday, just a short vid by John. Theres two models that he showed, the one that is more popular is that there is just a tube in the east rift which erupts at random locations, and there is the other model where the rifts are more fundamental and are active to the base of the volcano. I think out ideas are much more in line with the second model. The bit I dont get with first model is how the magma actually intrudes down, it wouldn’t really make sense for a buoyant liquid to sink. It also doesn’t really explain why there were no eruptions for long periods on the east rift, then lots over a similar period.
    The depth of the main conduit also probably decreases with distance from the summit, eruptions at the summit can probably be fed by lava that bypasses the magma chamber entirely – 1959, and these deeper set intrusions can probably also move along the rift at depth and probably quite slowly and with little seismicity, this was also observed in 1955 and 1960 where quakes only really started beyond heiheiahulu, and in 1840 there were few noticeable quakes at all. 1924 seems to have been a pulse of magma but there was not enough stored magma to cause an eruption. This year was probably not as deep because it started from the middle of the rift, so it was already higher up.
    This deeper part might actually be the reason for the distribution of shields on the east rift stopping quite abruptly, these eruptions could be fed from quite deep and not directly from the upper summit reservoir but from deeper storage areas. Maybe in around 500 AD something shut off the east rift and so all the magma had to go through the summit, but over time it managed to get around this and so now it is more preferable for lava to erupt out of the east rift slowly.

    • I am more of a fan of the tube model though. It can perfectly explain the periods of low and high activity: when activity is high the tube exists and then an event would cause it to drain away and partially collapse entering a period of low activity until the conduit slowly starts recovering. One model is not incompatible with the other either, some eruptions could be using deeper part of rift like 1840 or 1924, particularly when the conduit is not present and then the conduit would feed shallow dikes that intrude oblique to the direction of the conduit and would allow sustained shield-forming eruptions to keep going. HVO probably sees it as a permanent structure and there is where I disagree.

      I do think that there is enough evidence for the existence of a conduit as without it it would be more difficult to explain some features of the UERZ mainly how magma is transported oblique to the direction of dikes, the weird seismicity of the upper ERZ and the existence of reservoirs (which probably form along this conduit in those places where it cuts the dikes as the conduit itself develops). I am not sure if tube would be right way to refer to it or how intrusions like 1840 that are probably not intruding through it work.

      • I know what you mean but I think it is not a simple shallow structure. At the very least it must lie some km below sea level if fountains as high as 500 meters can erupt from it – these require a substantial run up. I also don’t think the rift is open all the way through under kapoho, probably only as far as to heiheiahulu and covering the area where shields are formed. Typically events in the lower rift are very seismic but only from beyond the heiheiahulu area, before that it is basically silent. Even in 1924 this was the case, despite there not being enough magma to erupt during that event. I would imagine this structure to be pretty deep, probably extending nearly to the base of the volcano near the start of the rift but getting shallower further along, and intrusions branching off the end of it or straight up, but not down. In cross section the conduit would also probably be oval shaped being much taller than it is wide, but still much wider than a single dike on its own. The same sort of thing but smaller probably exists under the seismic SWRZ and a more localised magma body under kilauea iki but no shallow magma under the part between hi’iaka and keanakako’i craters or the northern part of the caldera. The volcanic SWRZ seems to be entirely superficial and fed from the now destroyed halemaumau reservoir. It’s activity seems to occur within the top 1 km of the volcano and at it above sea level.

        • If you ask me I don’t even think the conduit existed by the time of the 1924 intrusion, if anything it was starting to form in the uppermost rift, the area of Pauahi and uprift. There was a publication where they inferred a reservoir 4 km below the sea level under Napau that would have been reinflating after the 2011 Kamoamoa fissure, it is probably the only mention you will find to this Napau reservoir but it makes perfect sense to me, its location and depth. This Napau reservoir would be directly feeding the Pu’u’o’o dike which would basically radiate from there and would mark the depth of the ERZ conduit, only if the location of the reservoir is right.

          Within the top 1 km of the volcano might be unnecessarily deep as the dike thought to have feeded the 1919-1920 Mauna Iki eruption was exposed on the walls of the 1924 collapse,if someone had decided to dig a hole some tens of meters deep between Mauna Iki and the summit it might have found a fiery surprise. The Seismic SWRZ on the other hand is much more similar to the ERZ and probably also has a conduit on its uppermost part that is a few km deep, it has the same linear swarm of earthquakes at a depth of ~3 km the UERZ has, and this depends on the intepretations of which one of them is that it represents the roof of the magma conduit responding to pressurization.

        • Apparently during the onset of the Mauna Iki eruption many cracks propagated from the summit to the 10 km downrift vent and these cracks where observed to be filled with with lava (or would it count as magma?) but didn’t erupt to the surface, so the dike was practically in the surface but would’t be able to build enough pressure to erupt upwards. So I wonder how could the dike have enough pressure to propagate downrift but not to send magma upwards, I guess the cracks were already mostly there, ready to be intruded. Kilauea does some weird things sometimes.

        • It is also quite noticeable that this line on the rift seems to go exactly along the rift axis, while the fissures of other eruptions all orient parallel along the koae faults and east rift. This point might be the actual gap between the mobile south flank and the less mobile flank of mauna loa, and as such a convenient weak point that would allow superficial drainage of magma from the upper summit system. The lowest of the 1823 vents was at 30 meters above sea level so the dike was probably about 1 km deep under halemaumau, mauna iki would have been probably even shallower as you suggested, there were a lot of fairly randomly spaced vents there in 1919, some of them were probably from lava at a main vent flowing into old lava tubes and making rootless vents, I guess maybe the lava was just not pressurized enough to properly erupt, the lava lake then was about twice the size of the overlook crater lava lake, impressive, but not very much lava compared to the volumes in most flank eruptions. Overlook did drain and an intrusion from the south caldera reservoir almost erupted in 2015, it probably stopped because the dike reached equilibrium with the lake and as the ground above the dike was about 200 meters above the lake it was not enough to erupt. This spot might be important in the near future, it could form a pit crater or fuel some eruptions.

          Mauna iki is basically in line with the great crack which fed the 1823 eruption, and the 1971 vents reused the mauna iki fissure, and in all cases there was summit activity with or just before these eruptions, in halemaumau.
          1974 was obviously very different, being a deep fed and very voluminous eruption that was erupting very primitive basalt similar to east rift eruptions. That eruption would have been incredible to see, it wouldn’t have been too much different to holuhraun at its start, except it only lasted 6 hours – a mini flood basalt. The lava flowed most of the distance after the eruption already ended…

          • The great crack is better is line with the Seismic SWRZ, it is dificult to tell to which of the two does it belong but since the Seismic SWRZ was very active in the years before 1823 (Kamakalia, Kealaalea) I think 1823 is part of the Seismic SWRZ. It is also dificult to tell if the Great Crack was there already or if it formed during the eruption. The volcanic SWRZ would first show its activity after the 1868 earthquake maybe a deeper intrusion in that case since the summit collapse and I don’t think the simultaneous eruption at Kilauea Iki was responsible-

  35. Two new stars at Barda, Iceland and a small 1.0 shake under Hekla…

    • Triple star now. And one of the quakes was quite large, M4.5

      • I suspect the M4 and the M4.5 are two versions of the same quake since only one is 99% quality and they have identical timestamps. The M4 is what the automatic system detected and the M4.5 is the manually verified. This happens from time to time and the one with lower quality usually disappears after a few hours.

        Looking at the CSM graph and assuming a constant average rate, there should be enough built up strain by now for another one of similar size or larger.

  36. Bardarbunga wont erupt
    All the quakes are tectonic in origin and its the caldera plug faults, that interacts with the mid ocean ridge.
    bardarbungas upper parts are free from magma and quakes alot.
    Still the volcano is refilling at great depth, but some quakes close to – 30 km suggest its quaky and brittle and great depth. Bardarbunga is not a very active volcano, but it have capacity to do some huge eruptions.
    Still there is lots of large lava flows outside Bardarbunga, suggesting very large infrequent eruptions.
    There is also a fault and transform faults in these areas.
    Holhuraun drained Bardarbungas upper magma system.
    Most of the magma goes into the spreading volcanic system and never erupts.
    There will be a long time until this volcano erupts again.
    Im supprised that bardarbunga have had so few histroical eruptions, despite it sits near the center of the Iceland hotspot.

  37. Im also curious of what kind of prehistroic event… that formed Bardarbungas 11km wide and 700 meters deep caldera, that coud be a strong VEI 6 in volume or even VEI 7
    Is Bardarbungas caldera acossiated with the Thjorsahraun eruption 8000 years ago? 30km3 drained out.
    Thjorsahraun is like Holuhraun 2014 but 30 times larger!

  38. Jesper, there is one thing you can take solace in. As long as there is a non-zero probability of something. It will happen… eventually.

  39. If you want a direct experience of volcanoes near Japan, without leaving your armchair, I highly recommend Willard Price’s Volcano Adventure. He wrote adventure books for boys, and the first half dozen of the books he wrote are very much based on first hand experience. I decided the book was would be too risky for my 90 year old father to read with his dicky ticker. The later books are very weak. However he gets his characters into volcanoes in a very risky way, experiencing eruptions that are really too close for comfort. The map with this article helps place where some of them might have occurred. The books are based around real events in real places. Well worth a read

  40. Thjorsahraun, must have been a quite impressve sight, av event about twice the size of Laki
    How fast Thjorsahraun was we cannot know, but since that eruption did not form a shield and the lava flow is 142 kilometers long we can assume it was quite fast to very very fast.
    I imagines huge fountains 800 meters or much higher and huge rivers of lava gushing like a spring river in flood. I seen many huge old basalt flows near gullfros.. suggesting that Iceland do these things quite regularly

    • Wasn’t very energetic then. According to witness accounts, Laki’s fire curtain ranged from 800 to 1100 meters in height across several km of the rift.

    • I think that is probably would have looked like holuhraun or fissure 8 most of the time, at that sort of eruption rate the vent tends to just erode out from the heat and becomes too wide for any real fountains, as well as often drowning itself in a lava lake. The eruption rate doesnt change so much but it is basically a hole in the earth at that point. Thorsja would have probably had to have sustained eruption of hundreds of m3 per second for at least a few weeks for the lava to flow that far. the lava from fissure 8 took 4 days to flow 13 km at about 150 m3/s. Thorsja is about 10 times longer so it probably would have taken maybe as long as 2 months to flow as far as it did, though maybe only a few days to a week to flow to near where hekla is as it is a valley up to that point.
      The alternative is that it was actually just as intense as the skaftar fires (definitely plausible) in which case it would have covered the distance in days to weeks with an eruption rate of thousands of m3/s. The start of holuhraun saw its lava flow advance several km in the first day at about 1000 m3/s and that started on wet ground like most of what thorsja was flowing over.

      I looked back at one of the posts by Albert where he worked out some of the numbers for the then rapidly intensifying eruption on kilauea. At that point the eruption was only 0.05 km3, but was estimated to contain 40 megatons of tnt equivalent in thermal energy. That eruption in the end was 24 times bigger than it was back then, a massive 1.2 km3 volume that is unmatched by any other eruption like it in hawaii since its original discovery way back around 600 AD. That would give the energy of the eruption as 960 megatons, twice the energy of all the nuclear tests conducted up to this day. If it was an explosive eruption it would be a VEI 7 almost 20% bigger than tambora…
      Not bad for the “worlds most harmless volcano.”
      Holuhraun was 50% bigger than that, at 1.8 km3, so it would be 1440 megatons, nearly twice as big as tambora, and bigger than every explosive eruption after 1815 combined…

      Still these pale in comparison to skaftar fires, eldgja and thorsja. Skaftar fires comes in at around 18 km3 of magma total, 10 times more than holuhraun. 14400 megatons, equivalent to 10 times the worlds nuclear arsenal, or a much larger VEI 7 bigger than any actual event in the holocene epoch. Eldgja is bigger still, 21 km3, 16800 megatons. Then we get to thorsja… 35 km3, 28000 megatons… That amount of energy is equivalent to 117600 petajoules or 32667 terawatt-hours, and it could power the entire earth for over a year.

      These 3 eruptions all on their own account for a very significant part of the earths entire volcanism in the holocene. Their combined energy is 59200 megatons, equivalent to 1184 tsar bombas, or 74 tamboras, or a couple of sizable VEI 8s.

      • It wasn’t 1.2 km³, it was 0.76 km³ based on data from HVO which makes it roughly half of Holuhraun. Where did you get your figure from?

        • I think Birdman means the volume that was lost into the ocean and combined with avarge eruptive rates during the summer months

          This is How he re – calculated the Puu Oo eruption to 11km3
          The numbers are conterversial
          But its very very likley he is correct
          Kilauea is a very impressive volcano for soure

          • After all 70% of Puu Oo eruption volume ended up into the ocean I think I read from USGS long ago
            4,5km3 is what remains on land and some places its more than 10 meter thick. Numerous layers of inflated pahoehoe. 1983 – 1986 was the most intense phase
            With giant fountains and huge Aa lava flows

            1986 – 2000 was pretty impressive too

            2006 – 2011 was impressive too in eruptive rates from Puu Oo

          • The thing is that I think HVO estimated the volume from the rates measured at fissure 8, that way they don’t loose volume to the ocean in their calculations and they also probably are aware of how thick the lava delta is. So if they calculated the geometry of the channel and the speeds of the lava right then they should have got the right number.

          • That is exactly what I did, basing it off the most widely reported number for the eruption rate – 140 m3/s. I don’t know where the 98 m3/s figure comes from, it was used during the actual eruption but afterwards it was discovered the channel was deeper than they thought so it must have been higher than that. Anyway I found the volume of lava from fissure 8 alone to be about 1 km3, and the volume erupted just before that to be a bit less than 0.2 km3. This even completely avoids the fact the flow is 300 meters thick in the ocean. As much as I respect HVO it does seem like their numbers are somewhat inconsistent with the volume you would get from actually having that much lava erupt at that rate for the duration of the event. Kilauea might be particularly prone to this, any eruption of even moderate size there will reach the ocean and it is hard if not impossible to accurately measure the volume of submarine debris below a lava ocean entry. Given that there were extended periods of time where pu’u o’o was discharging its entire volume directly into the ocean for months without any surface flows you can see where this goes.

          • The number I remember is of 100 m³/s and 150 m³/s was for the surges. I don’t think the lava delta reaches the thickness of 300 m either, it is probably around 150 m deep towards the tip of the new cape from what I have seen.

          • On google earth I made a map of the new lava based on a file HVO made and I found the spot at the est tip of the flow to be -290 meters. Google earth isn’t that reliable underwater but I wouldn’t expect it to be twice the value it actually is in real life. The sea drops off fast on the south coast of Hawaii, it is 1 km deep only 2.5 km off pohoiki. really the fact the flow went as far as it did is impressive in its own right.

          • On that the depth of the ocean at the end of the flow near ahalanui is about 400 meters, that is just for the bit where the flow is still above sea level, there would be some more going on even further underwater, this is the main part of the ocean entry. At kapoho it much is less and about 130 meters.

            Also to do with the eruption rate, I saw a video of a presentation by HVO that included a mention of an increase of the summit collapse by a total of 144 m3/s, and because nowhere else on the volcano was showing inflation, or any deformation at all, that means all the magma was leaving at the eruption point at the rate required to drain the summit with that volume increase. Fissure 8 was main vent from May 28 to August 3rd, a total of 67 days, and during that time it was pretty consistent at the rate of subsidence. There are 5788800 seconds in 67 days, so 5788800 x 144m3/s = 0.83 km3. This isnt quite as high as before but it is already more than 0.7, and this is only for fissure 8, the malama ki eruptions in the 10 days before fissure 8 erupted were going at the same rate but less concentrated at a single vent, and so that would add another 0.14 km3, making the total 0.97 km3, and then adding on the lava from before May 18 (mostly from fissure 17), brings things up to around 1 km3 pretty neatly. Not quite as big as my other estimate but rather more than the HVO number.

            This still means the eruption in kilauea is the energy equivalent of a tambora sized VEI 7 and it isnt going to take 100,000 years to properly recover either, probably about 1-3 years, maybe 10 years at most. Thorsja, eldgja and laki are a big fraction of the earths holocene volcanism, but kilauea is a much bigger fraction again. If kilauea has erupted at the rate average of 0.1 km3 every year for 12,000 years, then it would have erupted 1200 km3 of magma since the holocene started, and that much thermal energy is equivalent to 960000 megatons of TNT…
            Assuming tambora as a base, a VEI 7 of 50 km3 of dense magma is 800 megatons, there have been only about 7 confirmed holocene VEI 7s, that is 5600 megatons, with a fair diversion up to 6000 because of massive variability with VEI 7 size. Adding VEI 6s, assuming 1/10th of a VEI 7, 80 megatons, there have been 51 of those, so another 4080 megatons. VEI 5 is about 1/10th of a VEI 6, so 8 megatons, and there have been 175 of those, 1400 megatons. Adding these all up, you get a total of 10480 megatons, about 1/90 of kilauea… This also goes off the numbers from (https://www.volcanocafe.org/puna-in-numbers/). In that, the heat capacity for basalt is slightly overestimated, in real life it is 0.83 kJ/kg. However those numbers significantly underestimate both the temperature and density of hawaiian basalt, it assumes a density of 2.5 when it is actually about 3, and a temperature of 925 C when it is actually about 1200 C. Overall though it doesnt really matter, because kilauea is still two orders of magnitude bigger than almost any other volcano on earth…

            Still, at the Deccan traps maximum, it was about 600 times higher than kilauea ._. Really the dinosaurs stood no chance, the impact made it quicker. In a 12000 year period ‘coincidentally’ covering the K/Pg boundary, 720000 km3 of magma was erupted, its basically a skaftar fires that lasts 10,000 years without stopping. That amount of thermal energy is 576 million megatons, or 2.409984×10^24 J, enough energy to heat the entire atmosphere up by 1000 C if it was all released at once. Luckily it wasnt, obviously, but it would have heated up the earth a lot anyway even ignoring the huge amount of CO2 released by the event, and if you dont ignore the CO2, it would have trapped all that heat in and basically made the earth into a hell planet, not as bad as venus for sure, but very hostile for anything of any large size. SO2 might have reflected the sunlight but this was a rather redundant victory when the heat is coming from within, plus SO2 is extremely toxic to birds, much more than to mammals, so that also doesn’t help when dinosaurs had bird like lungs…

  41. Thjorsahraun coud easly have done that too,
    It was likley much much larger than Laki at start IF it went faster.
    When Thjorsahraun broke out.. you likley had a row of supertall fountain columns
    Lava fountain columns of Thjorsahraun( the black part ) likley reached near 20 kilometers tall at start.
    The main fountains ( red part ) later was likley as tall as Laki or somewhat taller ( 2000 meters ).
    As that eruption went on… the lava woud pool in the large vents forming dome fountains and fast rivers.
    This event released around 30km3 of lava and beacuse the flow is massive and narrow and long over almost completely flat ground, its a sign it went very fast indeed. Eruptive rates of perhaps 6000 cubic meters a second during the majority of that eruption and perhaps 15 000 cubic meters a second at start.
    The lava flows from this was mostly Aa and smooth pahoehoe in channels close to the vent.
    It must have flowed like a raging river in spring flood.
    Thjorsahraun crashed into the Atlantic 140 kilometers from the vent.
    Its Laki 2X. It must have been an impressive scene from space.
    Most of Thjorsahraun is buried by sediments from 8000 years of glacial floods and river sedimentation so its hard to estimate how large that flow is. Thjorsahraun have a compostion thats very similar to Holuhraun.
    One of the largest holocene flood basalts

    Thjorsahraun and Laki and Eldgja are impressive, but they are totaly dwarfed by the Largest flows from Deccan Traps and Siberian Traps and Camp flows
    Souch flows from these can have volumes of 5000 to 15 000km3 !

    • A 20 km tall lava fountain would be impossible, the energy needed to do that would pulverise the lava into ash. This doesn’t mean that much energy wasn’t actually there, but that the fountains would have been more like plinian eruption columns at the start, before eroding the vent and flooding out. 1477 could have actually been very analogous but didn’t have enough magma to give a big flow afterwards.
      In this case, thorsja evidently wasn’t just a lava flow, it probably had flow rates of similar scale to skaftar fires, except it either went longer or had twice the eruption rate. If it went longer then the volume of lava at the end of the flow would eventually be enough to extend it further than the supply rate would otherwise allow, this is like a pahoehoe flow but scaled up. If it was instead just a simple a’a flow then it was much more vigorous and pretty much exactly what most people would imagine a lava flow that big would look like.

      Also yes, a thorsjahraun sized event is definitely possible now, the rate of really huge rifting fissures was higher in the early Holocene, as were shields, and then they have declined. However while shields have stayed low since the mid Holocene, the last 1200 years has seen an increase in massive rifting fissures, eldgja and laki are the 2nd and 3rd biggest Holocene lava flows in Iceland, and both of them are very far from early Holocene. Bardarbunga won’t be doing the next monster flow though, it hasn’t got it after holuhraun. Personally grimsvotn and related volcanoes are the biggest threat, even if that was where the most recent massive flow happened from.

  42. That eruption coud be behind Bardarbungas main caldera formation.
    It was an event like Holhuraun but 30 times larger.

    Laki, Eldgja suggest these events are very possible again.
    the slowing of rapid Postglacial rebound and decompression melting .. wont slow down the chance of these events happening again. One day… there will be a new Thjorsahraun and world news and media storm.
    I wonder when the dead zone goes crazy again
    Katla and Vatnajökull seems most likley to do these stuff.
    Likely wont happen in my lifetime but sometime it will happen again.

    • Speaking of the deadzone

      23.10.2018 – 16:36:53 – 1,1 km – 1,3M – 72,73% – 23,4 km VNV af Kirkjubæjarklaustri

      • Let’s see if it survives the review. At the moment it’s on the tip of the Grimsvötn fissure swarm.

        • Which site did this image come from? I’d love to see more of this map!

          • It’s the VC Icelandic Mammoth map, there’s a copy of it as part of the eruption poll I did a couple of weeks ago. It’s still a work in progress due to small children at home and no time to update it. I use this map on a modified copy of the 3D Earthquake plot code that I’ve been tinkering with. Once both projects are done, they’ll be available on here for reference.

  43. Swarm in Bardarbunga
    Nothing eruptive.. just the caldera plug interacting with the mid ocean ridge and spreading faults and its the plug that is still settling.
    This is normaly a very noisy volcano earthquake wise

  44. Now Imagine the very largest flood basalts
    Like largest flows from Deccan and Siberian Traps and Opening of the Atlantic. 😛😬😏😏😏

    Souch individual flows coud have volumes of 5000 to 15 000km3 or larger!. This is a VEI 8+ effusive eruptions. In the most scary examples you can have fissures ( 300 to 600 km long ) Some old dykes in earths crust are many 100 s of kilometers long some over 1000 for old Canada LIP dyke swarm I think. These fissures with huge lava fountains roaring all over its lenght. Lava flow rates like the biggest jökulhlaup you can ever Imagine.

    Beacuse major LIP flood basalts caused global warming and Mass Exctiontions
    We can be pretty soure they went on very fast with collossal gas output.
    and the media image of magmageddon is likley quite true.

    Generaly true flood basalt lavas, are thick and uniform and massive: No lava tubes or small scale lobes: its fast and massive.
    A true massive ( 1000km3+ ) flood basalt
    Is likley a huge oversized channelized Aa flow
    With fast smooth Leilani like lava channels
    Flowing like mad crazy it must have done
    In the largest chase these channels coud be many 100 s of km long and maybe 40 km wide. Some lava flows from Deccan Traps flowed 1500 kilometers from their vent sources.
    The CAMP lava flow fields extended for over 5000 km over Pangea. It makes Holuhraun look like a little fart.

    At the distant edges of the ( +1000km3 ) Roza and ( +11 000 km3 ) Rhajamundry flows you likley have a massive wall of Aa lava moving quite fast 40 meters high and with some mouch faster breakouts that happens at Aa edges
    Or where the main flow front breaks thrugh the rubble.
    Behind the flow fronts is the main flow and open lava channels that looks like a lava sea from Closeup. The open lava channels goes up to the vent rift systems far away.

    The nightglow from these LIP events must soure been impressive red skies for 100 s / 1000 s of km photographers dream
    The initial startup of a (+ 5000km3 ) flow must have been an impressive sight for soure if its in the fast model the start up itself may generate A few VEI 7 volumes of tephra.

    Magnificent😏😏 I wants it
    But we all woud choke and sulfur smog everwhere and mass starvation
    If I gets it, I gets more than I can bite in
    Maybe its better that Flood Basalts are not Todays news

    • They would be terrible events. Imagine a 50 meter high lava flow coming at you at 20 km/hr. With deadly sulphuric air 1000 km away. Luckily they are very rare. For global warming, we are actually doing as much ourselves as a flood basalt would. Only the Siberian traps did more, and it was lethal. We started global warming from a cold (and cooling) climate, so so far we haven’t seen many bad effects, apart from the drying out of the Middle East. But we are playing a dangerous game.

      • and i miss the forest that is now Sahara Desert. Spending time on Google maps is really revealing at how much land is baren and unkind. i tell my kids and grandkids that they live in someone’s paradise….. forested mountains with plenty of water when they get tired of the cold and mosquitoes
        https://www.youtube.com/watch?reload=9&v=MzAZKeSBigM

        Best!motsfo

        • disclosure…… i don’t live in this part of the interior… and this year there were few mosquitoes here… first summer i’ve seen so few…

  45. I often wonder why we live in a time when giant flood basalts are a thing of the distant past. Is this a geological phenomenon that has ceased as the earth has cooled? Or is it merely good luck that we have avoided a large flood basalt event?

    • According to this paper, they (large clusters of LIPs) have a frequency of ~170 MA. If the last one (if you don’t count Iceland) is the Columbia River Basalt at ~17 MA we may have some time to wait, thankfully. But, this wasn’t a large cluster event. There seems to be a higher frequency of smaller LIP events. There are numerous small cycles involving impactor events, hotspot tracks and continental break-up involved in these. I’ve seen figures from 10 MA to 20 MA. According to wiki there have been 5 in the last 100 MA, so 1 every 20 MA.

      • Hawaii is another very active LIP, mauna loa and kilauea combined are the same volume of basalt as the columbia river basalts and nearly all of that is less than 300,000 years old. Since Maui Nui started forming 2 million years ago there has been half a million km3 of basalt erupted, probably more as that is fairly conservative and doesn’t include that most volcanoes lose a lot of their mass through landslides after becoming inactive.

        In general though, conditions capable of creating a lava flow big enough to be considered a true flood basalt (1000 km3+) seem to happen about every 10-20 million years. This means that the next real flood basalt might be somewhere in the geologically near future, maybe Carls Norway post will be the spot.
        In my view though, a lava flow that in in the hundreds of km3 range would be basically a flood basalt anyway, just as a volcano that erupts 500 km3 of magma is basically a supervolcano even if technically not a VEI 8. Iceland is potentially able to do a lava flow within this range, and some of the submarine sheet flows north of Hawaii are probably in this range too. In both cases more will occur eventually.

        • So Iceland have a theoretical capability of a 500km3 lava flow
          Carl told me long ago.. that Grimsvötns deep magma system contains 500km3 of eruptible molten basalt… the whole vatnajökull complex is estimated to have 800km3 of magma inside the deep rift – plume plumbing by carl

    • Wel. Good luck is relative here. These events last longer than our history as a species so the eruption would be concidered the normal.

      In an uchronie where one erupts in the US. It would have gone unnoticed in the rest of the world for most of history. With its weird effects on climate concidered just the way things are on this planet.

      Columbus would likely eventually stumble on an empty continent. (Assuming the volcano blocks travel of early natives to the US.). Colonist would do expeditions and the eruption itself would eventually be discovered and concidered hell or some other forbidden land. Eventually we would understand it better as science processes and learn of its role on climate and such.

      We would discus it here as a interesting volcanic ongoing event like Hawaii and Iceland. Yellowstone would be forgotten as a small fart and we would worry more about it suddenly stopping. Citing the terrible effects small pauzes in the eruption had on our climate in history.

    • Many large flood basalts happen during break-up of continents. The demise of a supercontinent shows flood basalts. That is uncommon at the moment because the continents are pretty broken up already. But not all flood basalts do. The Columbia flood basalt failed to break the plate. Neither did the large Siberian traps. Those can happen at any time.

  46. Terrible and Amazing! Flood Basalts have always been my favorite type of volcanism. For me who are addicted to large fast massive fluid basalt eruptions, nothing else can be better than that.

    For the largest events
    I imagines fissures many 100 s of kilometers long ( 500 km ) with many kilometers high lava fountains all along its lenght
    Give me armageddon

    If I coud be there near the vents when Siberian Traps and Deccan Traps and Camp was at its peak.. Nerdvana woud be achived.
    Give me oxygen gas and endless food and water and I coud spend my whole life: going around looking at erupting Siberian Traps vents.
    I imagines giant … rivers almost river dam break flows of lava.. turbulent and flowing extremely quickly. And ”seas” of lava that pools near the vents 150 kilometers wide and 100 meters deep
    The pyrocumulus and convective weather near the vents of these huge basaltic flows must have soure been impressive as heck!

    The problems woud be the Sulfur gas
    Areras for 1000 s of km around will become quite unbreathable and specialy downwind of the fissures, weeks after the start of souch a ( 10 000 km3 flow ) the world gets smoged by a yellow haze its Laki Haze but much much much worse.

  47. Superontinents acts as a lid, overheating the mantle
    Pangea prevented earths mantle there from loosing heat.
    201 million years ago.. that resulted in a major superplume ( hyperplume )
    The lava flows have long since eroded and broken up by seafloor spreading.
    This formed the enromous flood basalt Central Atlantic Magmatic Province
    Thats one of the largest lava flows to ever flow over land. 12 million km3 I think the original volume was.

    The lava flows extended 3000 km west to east and 5500 kilometers south
    The early dinosaurs got hell served. Lava flow rates maybe bigger than the biggest jökulhlaup you can ever Imagine. The gas output from the pangea pre – breakup LIP s was resposible for the hot and humid Triassic and Early Jurassic climates. the co2 output from these LIP s was collossal.
    This caused the triassic – jurassic dying event of fauna and flora and CAMP proivince is ofteb blamed for that.
    What an impressive sight CAMP must have been, fissures 100 s of kilometers long with giant fountains all over. The original CAMP plume head must have been many many thousands of kilometers across and have an astenospheric temperature good bit above 1500 C.
    Some of these flows was likley much bigger than the entire vatnajökull in volume 3000km3
    Some flows in Columbia River Basalts haves volumes of 10 000km3 (grande ronde )
    The mouch larger CAMP woud not supprise me if it had some flows close to 20 000km3
    This makes Hawaii and Iceland plumes seem like toddlers.
    That plume have long since cooled and died and been replaced by the cooler mar spreading.

    Then in Cretaceous an even more impressive flood basalt event Ontong Java Plateau basalts that erupted 100 million km3 of lava

    • I live in the heart of the Columbia Basalt country. the Grande Ronde flows
      run all the way to the Oregon coast Yaquina head is Grande Ronde basalt.
      My pet basalt pillar n my garden is from the Imnaha flows-which are older..
      Oh speaking of my pet Pillar.:
      Things seem to be active on the Juan De Fuca plate. Except the Cascadia fault. where the ‘old Demon lurks in his ice water dungeon…
      Hope this works..

      • Ok didn’t work there has been several 6+ quakes on the upper end of t he Juan De Fuca some down on the Gorda and Blanco end but nothing like this.. happens occasionally but i always wonder if these aren’t the precursor to the Cascadia unlocking… this is why I went home to the high lonesome of NE Oregon three mountain ranges and gigatons of basalt…
        I lived on the south coast of Oregon and had the china cabinet and other
        shelves bolted to the walls.. when things iike this happen I give my little Basalt column a hug…

  48. Coelophysis and Plateosaurus and Lystrosaurous and Desmatosuchus are one of the dinosaurs and other reptilian species that was lucky enough to see CAMP in action. I expect that many was caught in the lava torrents too as Pangea vent magmageddon. It happened 201 million years ago these severe flood basalts.

    Brave dinosaurs watching the giant fountains and huge raging mammoth sized rivers!
    Of course they did not knew a thing of what they watched or why it was so hard to breathe.
    The co2 and sulfur gas output was collossal, from these fissures, during short periods earth was likley as hot as periman dying. The dinosoaurs survived this depsite it was much larger than Deccan traps.
    A single flow coud be many thousands of times the size of laki at worst end.
    Most flows was likley many hundreds times Laki in size.

    The whole Mesozoic era was mostly very warn and humid.. these huge LIP events and superfast seafloor spreading of the young Atlantic released alot of co2 into the atmosphere and pushed up the sealevels.
    Today co2 is 400ppm but in Jurassic and Triassic it coud be at times many 1000 s of ppm.
    A warm and humid world without icecaps and flooded continents the dinosaurs had.
    When earth is very active and volcanism is high.. we gets a greenhouse era.
    After the dinosaurs died .. earth became less active and co2 lowered.. this gave us the Ice Ages.

    But now.. massive humans co2 emissions is like Albert says… just what the flood basalts did.
    If we dont stop burning fossil fuels we ends up in Eocene and Jurassic again

    • CAMP was far bigger than the Deccan traps in volume, but being on a rift it was probably subject to the same reason why Iceland isn’t a flood basalt, the rift steels a lot of the magma in spreading. Obviously this didn’t go quite as far with the CAMP, but a rifting flood basalt will probably never be as intense as a hotspot flood basalt. Back then dinosaurs were also way less derived than they were at the end of the Cretaceous. This is the same effect as why most of the mammals that survived the KPg event are now long extinct but modern mammals would be hard pressed to survive an extinction event.

      Deccan at its peak was basically like erupting the entire volume of Hawaii in 12000 years, it was also about as close as the earth has gotten to making its own olympus mons. At its height the Deccan traps probably was more like an enormous ponded lava ocean, maybe 100+km wide and hundreds of meters to over a km deep, constantly overflowing (with many overflows being km3 in scale), kept hot by its almost impossibly high effusion rate of a sustained 3000 m3/s over that 12000 years. I guess that it is possible that the rhajamundry flow was when this lake burst during a surge in the flow, possibly by an eruptive fissure opening through the edge and making a hole. By that point I don’t think there would have been any dinosaurs in India to observe it though. After that there weren’t that many dinosaurs left anywhere else either…

      I wonder if the combined CO2 release of the Deccan traps as well as its massive heating were why the last million years of the Cretaceous were marked by a sudden escalation in temperature and also why the earth was so hot and had so much CO2 in the atmosphere up to 30 million years ago?

      • Yes Thats true
        But CAMP was initialy formed by a massive hotspot! The CAMP plume head was thousands of kilometers across
        Huge dome uplift over Pangea
        The flood basalts coud have been just as intense as Deccan Traps or Siberian Traps

        The Pangea rifting was initialy caused by massive Superplumes
        And these plumes where much much stronger than African Superplume

        • Turtlebirdman:
          This is How I imagines the starting phase of a ( +5000km3 basalt flow ) looks like
          But Impossible incomparable larger than this
          Wolf fissure was kilometers long

          For Deccan Traps and Siberian Traps the initial curtains of fire coud be many many 100 s of kilometers long and many kilometers high
          Maybe 400 kilometers long
          Like scenes from some armageddon

          https://m.youtube.com/watch?v=N-WqKmisAFU

          • Yes at its peak Siberian Traps and Deccan Traps
            Likley was like a huge ponded perched lava seas near the vents. When it was in steady state mode
            Lava oceans 100 s of km wide and many 100 s of meters deep. Building giant versions of perched shields like Kupaianaha
            I imagines a lava sea from horizon to horizon
            Where the sea is feed there coud be huge dome fountains sending large waves over the grey skinned surface. And lava waves crashing against black glassy shores of basalt slag.

            This kind of stuff woud happen when a massive ( +1000km3 vent system ) calms down and goes into steady flow mode, when the vents have opened up and enlarged and merged togther.

      • But the initial startup of a ( 1000 /
        10 000km3 ) flow must have been nightmarishly impressive 😏😏😏😏😏😏😏😏😏😏😏😏😏😏😏😏😏😏
        I wants it!

        Just Imagine huge lava fountains over fissures that can be many many 100 s of kilometers long. Some old dykes in Earths crust are close to 1000 km long.
        Suggesting fissure eruptions can reach unimaginabe proportions.
        Souch events woud cause enormous problems if they happened today.
        Enormous ammount of Co2 and Sulfur

        On Venus flood basalts are even larger than on Earth, one lava channel on Venus is around 6800 kilometers long!
        I wonder how that formed, the eruptive rates must have been crazy
        That lava channel is around 500 million years old. Eruptive rates of mammoth proportions must have been needed to make a lava channel thats ( 6800 km long )

  49. Thank you everyone! That was interesting. So a few million years to wait, eh? I’ll have a word with my doctor, see if he can give some more pills to keep me going.

  50. Does any one want to comment on the signal on most of the seismographs around Mauna Loa. Looks like harmonics, it is happening now. From MOKD, Wild, Dand, …..to the shore CACD, KAPD. There is a little rain around, winds are light, and the surf for most parts are 2-4 feet, I thought I would need to see more surf to say that it was the weather.
    Enlighten me!

    Mac

    • Should have been more specific, started around 15:40 utc and ended around 16:20.

      • There have been more northwest flank earthquakes, 3 today and 2 yesterday, but activity is much lower than in early this month. The signal would seem to me to be stronger in the upper SWRZ and northwest flank so could it be related to an intrusion there?

    • That looks very similar to the lahars of Agung. A rain storm on the eastern slopes of Mauna Loa, perhaps?

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