Wrangell Mountains

Wrangell Mountains. Source: https://endlessloopphotography.com/2016/08/09/the-alaska-highway-and-wrangell-st-elias-national-park-canada-and-alaska/

Alaska is a wonderland. The harsh winters make the land difficult to live in, and in consequence much of the wilderness seems hardly touched by human hand. No need for rewilding here – it is wild enough to begin with! Amidst the wilderness are the most majestic mountains of North America, and some of its most impressive volcanoes. Among these are the Wrangell mountains. Anywhere else, mountains such as these would dominate the region. Here, they live in the shadow of other, better known mountains. The Wrangell mountains are a volcanic region, build up relatively recently by eruptions. Mount Wrangell itself, over 4317 meters tall, remains an active volcano. But underneath runs a deeper history, and lies an older volcanic field. The Wrangell Mountains are build on an ancient volcanic history, which played an important part not only in the building of America, but in the evolution of the Earth.

The Wrangell-St. Elias National Park is the largest protected wilderness in the United States. To give it a European scale, this park is larger than Switzerland. The Wrangell Mountains take up about a fifth of the park. To the southwest are the St Elias mountains, extending into Canada. All the mountains here are volcanic, and almost all are impressively high. Mount Bona, in the adjacent St Elias mountain, is the tallest US volcano, beating such giants as Mauna Loa. It is a bit of a cheat, though, since only the summits are volcanic. The volcanoes grew on top of an already highly elevated range. They are among the tallest volcanoes in the world not by their own effort, but because they grew on the shoulders of giants.

The Wrangell and adjacent Elias Mountains. Dotted areas indicate glaciers. Source: Richter et al. 1995, USGS Bulletin 2072 https://pubs.usgs.gov/bul/2072/report.pdf

The individual Wrangell volcanoes are described very well in the Guide to the Volcanoes of the Western Wrangell Mountains, Alaska-Wrangell-St. Elias National Park and Preserve, by Donald Richter and collaborators, published by that most open-access publisher of all, the USGS. (It is USGS Bulletin 2072, https://pubs.usgs.gov/bul/2072/report.pdf.) The information in this post comes to a large extent from that highly recommended source.

Volcanoes in cold storage

The oldest volcano in the Wrangell mountains is also its highest peak, Mount Blackburn; at 4,996 m it is just shy of the 5 km mark. It was named after the US senator Joseph Blackburn, well-known in his time but now remembered only because of the mountain. The naming was a bit of a long-service award for his public career. Mount Blackburn is rather older than the senator, though. It began to grow 5 million years ago with a granite intrusion. Volcanic activity came later, and the shield began to build. Around 3.4 million years ago the 5-km wide caldera collapsed. Andesite lava was ejected from the circular caldera fault at this time. These are the only Blackburn lava flows which have survived the subsequent erosion. After the caldera collapsed, the volcanic activity ceased.

Mount Blackburn. Source: wikipedia

Skookum Creek Volcano


Now the activity moved 50 kilometers to the north, where around 3 million years ago Skookum Creek Volcano began to grow. It started with basaltic lavas, followed by much larger andesitic flows. In its heyday, Skookum developed a caldera 14 km across. Activity ceased 2 million years ago; most of the mountain has since eroded away. The caldera rim disappeared in its entirety, and only the lava flows erupted within the caldera remain. The mountain is 2,172 m tall, and is only a shadow of its older self.

After Skookum became extinct, activity shifted southwest, to Tanada and Jarvis. Tanada is around 1.5 million years old, and like the other volcanoes here it experienced caldera collapse and died. Jarvis was active at the same time but grew larger. It is still over 4 km tall but is now deeply eroded. There may have been two overlapping calderas but this is not fully clear. Both Jarvis and Tanada became inactive 1 million years ago. Capital Mountain became briefly active 1 million years ago but activity here ceased within 100,000 years.

Mount Sanford


Now a new series of giants began to grow, starting about 800,000 years ago. This happened to the west of the previous activity. The first stirrings were at Mount Sanford where lava flows from three separate centres build up smaller shields. The three centres were approximately aligned north-south and may have been part of a rift. The northernmost centre, uniquely, erupted a rarity, a rhyolite flow extending almost 20 kilometers to the north. The eruption then moved to the centre where it build up an imposing shield which incorporates the three older volcanoes. Sometime between 300,000 and 100,000 years activity here ceased. It has left a 4,949 meter high mountain with a spectacular 1.5-mile-high rock face on the south face. There may be a filled-in caldera but this is not clear from the structure.

The westernmost peak of the Wrangell Mountains is Mount Drum. It too is volcanic, and probably formed between 600,000 and 200,000 years ago. It is significantly lower than the other peaks, at a measly 3,661 meters, but this is not for want of trying. The bulk of the mountain was destroyed in an explosion that happened between 200,000 and 100,000 years ago. The current Mount Drum is only one side of the original mountain; the other side is Snider Peak. As much as 100 km3 may have been removed in the explosion. The last and presumably final eruption was between 125,000 and 150,000 years ago.

Mount Drum, with Snider Peak on the right. Source: google images

The last of the gang of three is Mount Wrangell itself, which is the only currently active volcano in the Wrangell Volcanic Zone. It too is a large shield volcano, build up by andesitic eruptions. Its current volume is about 900 km3. The mountain started to build up by 600,000 years ago. The youngest lava flows are about 50,000 years old. A cone next to Wrangell, called Mount Zanetti, may be only 25,000 years old. And there has been more recent activity.

The recent activity is shown in reports of eruptions in 1784, 1884-5, and 1900. However, the one in 1784 is highly dubious, in part because the mountain wasn’t discovered until 1819. The eruption is mentioned in a book on the geology of Alaska by the Estonian mineralogist Constantin Grewink, and is a second-hand mention of an eruption from ‘Chetchina’. There is a river of about this name near Wrangell, and therefore this eruption was subsequently identified as Mount Wrangell. However, Grewink himself assigns it to the Andreanof Islands, and it is now usually assumed to refer to Great Sitkin.

The 1884/5 eruption is also considered unconfirmed. This eruption comes from a report by a local prospector, John Bremner, who was about 30 miles from the mountain. It was a typical Wrangell winter, as is evident from his journal: ‘Clear but very cold the floor of my cabin is frose two foot from the fire and I thought I had made it almost air tight so you see I am in no danger of melting with the heat.’ (www.avo.alaska.edu). He reports seeing smoke from the mountain in December 1884 and on February 3 a very large column of smoke and ‘hurling imense stones hundreds of feet high in the air’ as well as a rumbling noise. Other people only reported the smoke. There may have been a phreatomagmatic explosion but the doubt comes from the fact that he was 30 miles away. At that distance, the ‘hundreds of feet’ corresponds to 0.1 degree, a fifth of the diameter of the full Moon: it is hard to see how he could have seen such detail as the ‘immense stones’.

That leaves us with the 1900 eruption. This was not directly observed but inferred: It comes from a report in the Galveston Daily News of June 10, 1902: “In June, 1900, I observed a black patch several miles in extent on the southern slope of the mountain, extending from the summit down to perhaps 11,000 feet elevation. As it was covered with snow when the mountain was next seen, about the last of September, it seems probable that the bare area was due to material thrown out by the volcano.” Another report from 1899 mentions an eruptive plume and a lava stream, although there is no confirmation of any lava. It is sometimes suggested that this may have been smoke from the fumarole patch on the southwestern flank of Mount Wrangell. However, it appears that such activity is not that unusual, and more dark patches stemming from phreatic explosions have been reported since.

Summit caldera of Mount Wrangell, with the rim craters. Two of the rim craters show a vapour column. Source: USGS

Mount Wrangell has an impressive summit caldera which measures 4 by 6 km, filled with 1-km thick ice. Along the caldera rim are three further smaller craters, imaginatively called: Mount Wrangell Crater, North Crater, and East Crater. North Crater appears to be the source of the occasional explosions. This crater has significant ground heat. It lost almost 90% of its ice between 1965 and 1984, at a time when the other craters showed no change in ice cover. This followed the 1964 Good Friday Alaskan super-quake (M9). Interestingly, the 1900 eruption was shortly after the September 3, 1899 Yakutat earthquake (M8). After this quake, there are some reports of increasing smoke coming from the summit. The possibility exists that these quakes opened up pathways for underground hot water.

These are the main volcanoes of the Wrangell Volcanics. Some smaller peaks are not included, and it is conceivable that some further, minor eruption centres were buried under the developing shields.

Time line

The plot below shows the time line of the Wrangell Volcanics. It began with a granite intrusion 5 million years ago, which developed into volcanic eruptions a million years later. Since that time, the activity has moved around, building one mountain after another but rarely more than one at a time.

Mud, glorious mud

Immediately west of the Wrangell Mountains is the Copper River valley, known for its large copper deposits. This area has mud volcanoes, where mounts of soil a kilometer wide and 100 meters high have been created by warm springs. They have the appearance of small shields. The 1 meter deep pits at their peaks produce warm muddy water and methane gas. The mounts are surrounded by dead trees, killed by the salty mud after activity here increased following the 1964 quake.

White Ash

A 50-cm thick layer of white ash can be found in areas surrounding the Wrangell Mountains. It is only just underneath the surface and clearly represents a recent event. Two events, in fact. There are two main layers, one to the north and one to the east, and radiocarbon dating of wood buried by the ash shows that the northern layer is older, and was deposited between AD 150 and 500. The eastern lobe covering a part of Canada came later, in an eruption several times larger than the first one. Tephra found in Greenland’s ice has given us a precise date: this eruption happened in the winter of AD 853 (a date 50 years earlier is also in the literature but is now out of date). Tephra from the explosion has been found as far east as Poland.

The two pyroclastic flows together amounted to a 50km3 eruption. These were two serious eruptions; the second eruption was large enough to cause the local population to migrate south and temporarily vacate the region.

White River Ash. Photo by Hugh Copland

It turns out that they came not from the Wrangell Mountains but from the other half of the park, the St Elias Mountains. This is a much older mountain chain, extending to the coast. The highest volcano of the US is here, called Mount Bona. The White Ash eruptions came from its lower, secondary peak, Mount Churchill. This is clearly a volcano with a serious temper. East of its current summit is a caldera 4 by 3 km across: this is likely the source of the ash, and probably the location of its summit before these events.

1: summit of Mount Churchill; 2: basin presumably caused by the white-ash eruptions; 3: location of an old dacite lava flow. Source: Preece et al. 2014, Geosphere, 10, 1020-1042.

Mount Churchill may have had a third, much smaller explosion 300 years ago which gave rise to a tephra deposit. But there is no evidence of older eruptions similar to the 853 event. This was a double one-off event. Churchill remains a riddle wrapped in a mystery inside an enigma.

Patterns

The Wrangell Volcanic Zone is not overly active. The eruptions seem to come in bursts, voluminous when they happen, quiet at other times. The volcanoes grow very large: clearly when a magma chamber has formed, it stays in place for a long time. The volcanoes all grow as a shield, and develop a caldera at the end of their evolution. These are not (strongly) explosive, but form because magma is withdrawn from the magma chamber. Where the magma goes is less clear! The calderas collapse to over a kilometer in depth, but much of this is filed in with basaltic flows which probably come from the ring fault. There are some similarities here with the formation of volcanic mares on the Moon. The magma is basaltic although there are differences from normal subduction zones. And one Wrangell volcano has produced this ultimate rarity, a rhyolitic voluminous lava flow.

Mount Churchill seems an exception, as it has produced at least two rhyolitic explosive eruption during the holocene. It is an offspring from the Wrangell Volcanic Zone, located away from the other volcanoes. The closest Wrangell volcanoes to it have been extinct for several million years.

The volcanic zone may be in the process of dying. There has been no large eruption for the past 200,000 years, and only a small region remains active. There is westward drift of the activity over time, and perhaps a new volcano will develop where the mud volcanoes are located. But there is no indication for this.

Subduction


The source of the Wrangell volcanics is clearly the subduction of the Pacific plate underneath Alaska. In this area, this plate subducts towards the northwest at a rate of 5 cm per year. The volcanic activity in the Wrangell Volcanic Zone has over time also moved northwest, although at a rather slower rate of 10 km per million years or 1 cm per year. The subducted plate begins to melt when it reaches a depth of 100-120 km, called the Wadati-Benioff Zone. The precise depth depends on the temperature and how wet the subducted rock is. At the point where the melt initiates, the newly formed magma begins to percolate upwards. At the surface, a volcano begins to grow. Obviously, these volcanoes are not near the subduction trench, but some distance down stream – how far depends on the angle of subduction. For shallow subduction the volcanoes will be at considerable distance, whilst for steeper subduction they are closer. The Wrangell mountains are further from the coast and one may expect a shallower angle of subduction.

However, things are a bit more complex. The Pacific plate subducts along the entire Aleutian arc, but volcanic activity is not the same everywhere. The arc of volcanoes ends west of Anchorage. Further east, there is a length of 400 kilometer without volcanoes, so unexpected that it has a name: it is called the Denali volcanic gap. The Wrangell Mountains are immediately east of this gap, and are a bit in-land, as a clearly separate mountain range. There is more here than meets the eye.

Next week

This is the first part of the Wrangell post. Come back next week to read about reluctant subduction, building America, and the flood that brought the rain.

Albert, January 2020

Alaska on a good day

63 thoughts on “Wrangell Mountains

  1. It is interesting that these shield volcanoes are also mostly andesite. By the way, none of the suspected eruptions at Wrangell are confirmed by AVO (including 1900) so it is unknown when it last erupted.

    • True. The 1900 event has stronger credentials than the others, being reported by three different people, but is not confirmed. It would have been a small phreatomagmatic explosion.

    • Ref the Andesite… the whole area is accretionary. It’s even got a name. “The Wrangellia Terrane”

      • Thanks to the rotation of the West Coast- the Seven Davils of Idaho have a goodly chunk of Wrangellia Terraine in them.
        A bit in the Hell’s canyon area too..-H/T Nick Zentner Central Washington University.. i don’t have time to look it up on You Tube..

  2. Interesting. i remember driving up the alcan for the first time many years ago and driving around the group Mt. Sanford and Mt. Drum. Time seemed suspended as we drove around and hour after hour it looked like no progress had been made. It was like we were driving on a huge belt of moving road travelling in the opposite direction at the same speed, cancelling all our progress. No matter how long we drove we seemed to be standing still and as the hours went by it was rather disconcerting. Best! from motsfo at minus 5F and probably going to minus 25F in the next few days…. every little twig is covered in frost and i’m hibernating till it warms a little.

  3. I remember my last trip to Fairbanks (Fire season 1992) in a DC7-due to weather.
    Hey, its Alaska. We had to divert around the north side of the Wrangells. I have seen the the Canadian Rockies, Denali , and the Rocky mountains. but nothing prepared me for looking UP a these massive giants… that same trip I fortunate to get Denali in a good photo-cloud free..

  4. I am quite surprised by the absence of volcanic eruptions in Iceland.
    Especially considering that we are in the maxima of a hotspot activity and it has been 5 years since last eruption.

    Maybe Betelgeuse, one of the sky brightest stars (but now strangely dimming) will explode as a supernova before any Icelandic eruption happens.

    As offtopic, and also on the “fires” topic, sad to see the massive fires in Australia. Very extreme weather patterns unfolding. I think 2019 saw an unusual area of fires across the world, considering also the fires in the Brazil, Bolivia, Siberia, Indonesia… That puts extra CO2 into the atmosphere, a classical positive feedback loop.

    Also concerned with the positive feedback loops currently happening in the Middle East. Does not serve us as a species. We are currently facing a hard time as a civilization…

    • Betelgeuse has some really strange convection going on. I have yet to see any science program that includes Betelgeuse that does not also mention it’s utter weirdness.

      (It’s only weird because we haven’t seen a lot of the stuff that it does before and the guys who study it have to jump through hoops to figure out what it’s up to.)

    • The amount of global fires has been decreasing due to the increased wetness of the warmer world due to evaporation from oceans. Deserts have also decreased in area and forest are expanding despite our worst efforts in the tropics. The benefits of CO2 fertilisation and warmth. If you study paleoclimatology then you realise cold is the enemy. The dark ages correspond to cold periods, the golden years are warm periods. Fortunately we have a couple hundred years hopefully till the next 1ky bond solar cooling and the catastrophic cooling of the little ice age we are recovering from seems to have been due to the conjunction of the 2.4k bray solar cycle and a 1.5k oceanic cycle. So the good news is we are unlikely to enter the next glacial cycle for a couple thousand years unless a big volcano gives us a push.
      CO2 is a non issue if you understand chemistry. A doubling of CO2 cause 3.7W/m2 of warming. (1 deg C) This was amplified by an additional 10w/m2 of positive feedback in the computer models in the form of increasing water vapour in the upper troposphere. The observations show negative feedback with water vapour decreasing, consistent with Le Chatelier’s principle, (the thermodynamic equilibrium law)

      The actual driver of climate is changes to cloud cover which is an order of magnitude larger than CO2 forcing. Thats why infra red emission to space are increasing, 2/3 of observed warming during the satellite era is can be directly attributed to cloud forcing. Yet despite this additional forcing not accounted for by climate models, the observed warming is only half that predicted from CO2 alone. The Positive feedback just isn’t there

      Here are peer review articles on the observed cloud forcing seen the the earth radiation budget experiment.
      https://res.mdpi.com/d_attachment/climate/climate-06-00062/article_deploy/climate-06-00062.pdf

      https://www.researchgate.net/publication/276497853_Late_Twentieth-Century_Warming_and_Variations_in_Cloud_Cover

      As for the current Australian fires, the indigenous owners used to burn twice this area every year, thats the only way that you can prevent fire here, reduce the fuel load. Other countries have ripped out their Eucalyptus plantations because of the extraordinary fire risk they pose due to flammable oils in the leaves.

      The huge quantities of smoke produce may actually help nucleate clouds and cause global dimming if anything.

      • If you need imaginary cycles to deny the blindingly obvious, you have a problem. The Australian fires are an absolute disaster for the locals and they need support, not denial. Years of extreme drought and now extreme temperatures with records in every state have caused this. Blaming the fire fighters for not doing preventative burnings is libellous. They have said that for years it has been impossible to do this because it was too hot and dry to do this safely at any time.

      • I take it you don’t live in Australia Rob; and if you do you are nowhere near a fire? I had to be evacuated from one that surrounded my village, saved by volunteer fire fighters. It is that hot and dry in Australia this season that the bush fires started in August – late Winter; and have burned through areas that have only recently been burned to reduce fuel. So far an area of 32,400 square miles, or 83,915.60 square km, or 25.5 million acres, or 10,319,484 hectares has burned this year and summer has only just begun. That is bigger than several European countries, or US states. Apart from the human costs to life and property, over half a billion animals are believed to have been killed already and several species are likely to become extinct. If our Aboriginal population were stupid enough to burn twice this area every year, they would have never have lasted 60,000 years on the land.

      • Here is a link to the official Australian Bureau of Meteorology/CSIRO 2018 State of the Climate Report. http://www.bom.gov.au/state-of-the-climate/State-of-the-Climate-2018.pdf.
        It’s predictions made over a year ago have come to pass.

        If it was up to me, our Prime Minister, an evangelist Pentecostal Christian fundamentalist; incapable of accepting any scientific advice that contradicts his religious views; would be charged with murder for causing death and enormous financial losses by willful negligence for failing to act on the advice his government was given by experts.

        His ridiculous religious freedom legislation would be repealed and any religion denying science and thus endangering life and property would be banned.

        • I remember that report. Page 8 talks about the drastic increasing chance of ‘compound events’. That is exactly what happened. I hope you, your house and your town are ok!

          I don’t agree with singling out christian fundamentalists, though. The anti-climate stance came originally from industry, not from them. Even as recent as 15 years ago, they were by and large in favour of caring for the environment, not destroying it. I see them as victims, who were hijacked. As a group they proved vulnerable to deception by people they thought were on their side. I see the battle not between science and religion but between science and industry. In Australia, the exceptional influence of the coal mines decides on the government. Experience has shown that any PM challenging the mines is out within months.

          Regarding religion, I see much in Gould’s idea of non-overlapping magisteria. The physics of global warming is most definite on the science side!

          • Religion might be closed to hypothesis but science never should be, even if someone argues AGW is false, just review the claims without bias, and offer an official explanation, that’s science.

            Also not sure but someone mentioned that they were reducing the number of prescribed burns because of the fear of CO2 release. Couldn’t that be shortsighted in some form or another from the climate extremists?

        • Try living with the deadly consequences of intransigent science denial and the imposition of religious freedom legislation to discriminate where they like when it comes to supplying goods and services like medical attention; then tell me I’m being a tad too authoritarian. I don’t single out Christian fundamentalists. I oppose all science deniers equally. I have decided to convert to “scientific evangelism” and preach Hell and Damnation to the lot of them with the same monotonous and tortured frequency that I am forced to tolerate their incessant, logiphobic drivel.

          However, apart from this one angry spray, I shall refrain from further flaming on this location.

          • No one can do science and at the same time have an agenda, pick one or do neither.

            Anyone who argues for AGW should be open to facts that prove otherwise and anyone who argues against AGW should be open to facts that prove it is so.

          • It is hard to disagree with that statement! Science has a procedure for this: if you pose a model based on the currently available data, this model should make predictions which can be tested in the future. For global warming, this discussion took place in the 1990’s. At that time, indeed, there were scientists arguing on both sides. You will find papers from this time about, for instance, the date in the year that a certain bird would lay eggs, and whether this was getting earlier in the year: if so, this would indicate a significant environmental change. In the 2000’s, the predictions of the global warming models were confirmed, and that settled the arguments. Of course we are still testing predictions: that never stops. There were prediction around 2010 that the southern Amazon rainforest would see increase in fires, and that has been confirmed. The greatly increased fire risk in South Australia was predicted, and has come to pass. The discussion is now on climate sensitivity. This is normally stated as the warming arising from a doubling of the CO2. The models find values between 2 and 4.5 C with some outliers. The most recent results I have seen have pushed the median up from 3.0C to 3.3C based on data that shows that low clouds contribute to warming. That is the current level of discussion: it is about model differences at the 10% level. But people who deny the data will not be convinced until their own lives become badly affected, by which time it may be too late.

  5. Received a strange email allegedly from Albert entitled “the last post” when you click on the link to get to the posting the link doesn’t work. What is occurring?

    • No worries. A back channel item was mistakenly put on the site. It was deleted when the mistake was spotted, but the email didn’t know that.

  6. I cannot get enough of these kinds of posts; never heard of before yet such interesting, much wow.

    On a side note, I’ve got an idea for an article. Can anyone tell me how many words that should be? Or how many Word-pages?

    • There are no strict limits. 1000 words can make a short snappy post, 3000 words is quite long, 6000 words is epic. We will happily consider anything. The one you just read is about 2500 words

  7. Thanks, Albert, for another great post. Looking forward to the follow-up.

  8. https://phys.org/news/2020-01-formation-huge-underwater-volcano-offshore.html

    Formation of a huge underwater volcano offshore the Comoros

    A new submarine volcano was formed off the island of Mayotte in the Indian Ocean in 2018. This was shown by an oceanographic campaign in May 2019. Now, an international team led by the scientist Simone Cesca from the German GeoForschungsZentrum GFZ is illuminating the processes deep inside the Earth before and during the formation of the new volcano. It is akin to detecting a new type of signal from the Earth’s interior that indicates a dramatic movement of molten rocks before the eruption. With their specially developed seismological methods, the researchers are reconstructing the partial emptying of one of the deepest and largest active magma reservoirs ever discovered in the upper mantle. The study is published in the journal Nature Geoscience.

    • Alert raised to Red now, first time for Shishaldin since 1999. I wonder if it will repeat that 1999 eruption.

  9. I knew volcanos is skookum as frig, but now I’ve got a picture to go with it! (Obvious AvE reference)

    Great article, can’t wait for part two!

    • I saw that this morning. Is it possible that the lava fields that buried the crater were in part caused by the impact?

  10. The Mauna Loa deformation is remarkably uniform. The caldera length increase fits a straight line for most of the past year. There was a wobble after August but it has gone back to the previous trend.

    • Mauna Loa either does spectacular Icelandic style rift eruptions

      Or more long lived Puu Oo like tube feed flows.

      Most of Mauna Loa is covered by pahoehoe in Google Earth suggest slower decades / centruies / millenia long tube – lake feed eruptions is the norm for Mauna Loa.
      The longest Mauna Loa slow tube eruptions lasted 1100 years in holocene I think

    • By eye, and from what’s shown, I would be tempted to suggest a quadratic would be a marginally better fit. This has nothing to do with falling caldera roof though, its the opposite way round!

    • Over a more long term it is very complex though, caldera lenght over the last decades:

      And also the last 5 years which overlapps in 2015-2016 with the previous graph to show the full picture.

      The current long dormancy has some obvious reasons, first that the 1984 eruption reduced pressure significantly visible as a decrease in caldera distance, while the 1975 eruption had a comparatively small effect. 1984 would be expected to have a longer recovery.

      It is also important that Mauna Loa currently has a very low supply, recent inflation is far slower than inflation before the 1975 eruption. Currently Kilauea is dominant over the hotspot with a supply many times higher, while the summit of Mauna Loa totals about 45 cm of extension since end of the 1984 eruption the summit of Kilauea has since the stop of the 2018 eruption inflated even more, about 50 cm of caldera lenght increase while at the same time inflating its east rift zone. Or in other words Mauna Loa will not have accumulated an extraordinary amount of pressure. When the eruption comes if it is at the summit it will be small (like 1975), if at the rifts probably similar to 1984.

      • Indeed Mauna Loa is loosing the Hotspot to Kilauea and Loihi

        DustDevil
        When will Mauna Loa start go go alkaline?
        Have the holocene magmas been ”less” Thoelitic than the main building phase during Late Pleistocene?

        Of course Pleistocene rocks are buried under miles of lava flow rock now ..

        • Mauna Loa and Kilauea are alternating dominance over the hotspot, for example Mauna Loa was dominant from 1840 to 1950 when it remained frequently active and very productive. Situation has reversed and I think that throughout our lifetimes it is going to remain like that, it might still erupt a few times this century though.

          Currently Mauna Loa is considered to be in its shield stage, I am not sure if magma is more alkaline or not but it remains well within the tholeeitic range. I think that Mauna Kea fluctuated between tholeeitic and alkaline for a long time before entering proper postshield so it might be like that for Mauna Loa, hard to say when will that start.

        • Is there any basalt type that is result of larger partial melting than Thoelitic Basalt?

          Or is Thoelitic Basalt result of very most partial melting possible in something thats classifyed as a basalt?

          • In the alkali vs silica diagram basalt is at the bottom, so there is no classification for something with lower alkalis, even if it had no at all it would still be called tholeeitic basalt…

      • yeah, well ok, its not at all simple, as would be expected. I think about all one can say with confidence is that activity is increasing. Having said that it will, of course, now decrease.

  11. Likely will be an eruption soon
    Mauna Loa is one of the most active volcanoes on the planet. It have erupted ”large eruptions” 33 times since 1840.
    More than almost any other volcano on Earth.
    Very productive volcano.

    The next eruption coud be rather large in lava volume as it have sleept for a while…
    Probaly will be the same fast short lived voluminous style as 1984 and 1950 s with large fountains and fast moving open channels.

    • Classic vulcanian eruption
      And bye bye pancake lava dome blasted away

    • That’s Popo and it is a very tall volcano. 5426M, so that was a big explosion covered at least 2/3 of the cone.

  12. Wow Wrangell Mountains are huge!
    This mountain complex is around 130 kilometers long
    Impressive indeed
    Its height is impressive too

  13. The on-going swarm in Puerto Rico has as expected gone bigger. The island was just hit by an M6 quake.

    • Downgraded to 5.9 after review. But my god. They just got the power back on and boom. Gone again. These poor folks can’t catch a break.

  14. just saying there are a lot of excellent scientists in my religion….. they don’t have to be exclusive of each other.

  15. Yesterday’s radar image of Anak Krakatau. It looks like the cone in the lake has itself developed a crater lake. A lake on an island in a lake on an island?

    • Like the “recursive volcano of Taal” in the Philippines: the island has a volcano: its caldera has a lake; on the lake there is a volcano, etc.

      • WTF! Right now I find out from the news that it has erupted (I didn’t know when I wrote the previous comment).

Comments are closed.