Volcanoes, including Mount Hood in the US, can quickly become active
Magma stored for thousands of years can erupt in as little as two months
New research results suggest that magma sitting 4-5 kilometers beneath the surface of Oregon’s Mount Hood has been stored in near-solid conditions for thousands of years.
The time it takes to liquefy and potentially erupt, however, is surprisingly short–perhaps as little as a couple of months.
The key to an eruption, geoscientists say, is to elevate the temperature of the rock to more than 750 degrees Celsius, which can happen when hot magma from deep within the Earth’s crust rises to the surface.
It was the mixing of hot liquid lava with cooler solid magma that triggered Mount Hood’s last two eruptions about 220 and 1,500 years ago, said Adam Kent, an Oregon State University (OSU) geologist and co-author of a paper reporting the new findings.
Results of the research, which was funded by the National Science Foundation (NSF), are in this week’s journal Nature.
“These scientists have used a clever new approach to timing the inner workings of Mount Hood, an important step in assessing volcanic hazards in the Cascades,” said Sonia Esperanca, a program director in NSF’s Division of Earth Sciences.
“If the temperature of the rock is too cold, the magma is like peanut butter in a refrigerator,” Kent said. “It isn’t very mobile.
“For Mount Hood, the threshold seems to be about 750 degrees (C)–if it warms up just 50 to 75 degrees above that, it greatly decreases the viscosity of the magma and makes it easier to mobilize.”
The scientists are interested in the temperature at which magma resides in the crust, since it’s likely to have important influence over the timing and types of eruptions that could occur.
The hotter magma from deeper down warms the cooler magma stored at a 4-5 kilometer depth, making it possible for both magmas to mix and be transported to the surface to produce an eruption.
The good news, Kent said, is that Mount Hood’s eruptions are not particularly violent. Instead of exploding, the magma tends to ooze out the top of the peak.
A previous study by Kent and OSU researcher Alison Koleszar found that the mixing of the two magma sources, which have different compositions, is both a trigger to an eruption and a constraining factor on how violent it can be.
“What happens when they mix is what happens when you squeeze a tube of toothpaste in the middle,” said Kent. “Some comes out the top, but in the case of Mount Hood it doesn’t blow the mountain to pieces.”
The study involved scientists at OSU and the University of California, Davis. The results are important, they say, because little was known about the physical conditions of magma storage and what it takes to mobilize that magma.
Kent and UC-Davis colleague Kari Cooper, also a co-author of the Nature paper, set out to discover whether they could determine how long Mount Hood’s magma chamber has been there, and in what condition.
When Mount Hood’s magma first rose up through the crust into its present-day chamber, it cooled and formed crystals.
The researchers were able to document the age of the crystals by the rate of decay of naturally occurring radioactive elements. However, the growth of the crystals is also dictated by temperature: if the rock is too cold, they don’t grow as fast.
The combination of the crystals’ age and apparent growth rate provides a geologic fingerprint for determining the approximate threshold for making the near-solid rock viscous enough to cause an eruption.
“What we found was that the magma has been stored beneath Mount Hood for at least 20,000 years–and probably more like 100,000 years,” Kent said.
“During the time it’s been there, it’s been in cold storage–like peanut butter in the fridge–a minimum of 88 percent of the time, and likely more than 99 percent of the time.”
Although hot magma from below can quickly mobilize the magma chamber at 4-5 kilometers below the surface, most of the time magma is held under conditions that make it difficult for it to erupt.
“What’s encouraging is that modern technology should be able to detect when the magma is beginning to liquefy or mobilize,” Kent said, “and that may give us warning of a potential eruption.
“Monitoring gases and seismic waves, and studying ground deformation through GPS, are a few of the techniques that could tell us that things are warming.”
The researchers hope to apply these techniques to other, larger volcanoes to see if they can determine the potential for shifting from cold storage to potential eruption–a development that might bring scientists a step closer to being able to forecast volcanic activity.
-NSF-
Sorry, o.t. but this might be worth a separate post, and not sure how to advise directly
Seems the Supreme Court is closely divided on Obama’s climate change regulations.
http://www.reuters.com/article/2014/02/24/us-usa-court-climate-idUSBREA1N06Q20140224
Ah well, as my late father, a sagacious man, used to say he didn’t mind living next to an extinct volcano but he was very unhappy about being too close to a supposedly dormant one. Wise words.
Kindest Regards
“What we found was that the magma has been stored beneath Mount Hood for at least 20,000 years–and probably more like 100,000 years,” Kent said.
…wait, don’t you realize what this means???
If it blows now, CLEARLY it was because of Global Warming! After all, all those years it didn’t blow BEFORE Global Warming; therefore it MUST be Global Warming which done did it.
pokerguy says:
February 24, 2014 at 1:09 pm
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Thanks for the heads up on that.
@ DS…I wonder if cooling would have the potential to increase volcanic and earthquake activity by causing crustal shrinkage?
Is this new information? Seems to me like it comes from the “Things We Already Know” department.
How can they blame volcanoes on CO2 and then tax us for it?
This will be the new question at the IPCC…
We actually observed that timeline in action at Mt. St. Helens (60 miles NNW of Mt. Hood) in early 1980. But, like A. Jones’ late father, do not want to be here when Mt. Rainier (100 miles N of Mt. Hood) next decides to let loose. We live 40 miles north of Mt. Rainier, and it’s a spectacular view, but it can be sobering to contemplate the energy beneath the peak.
Emails show that EPA Region 2 Administrator Judith Enck gave advice to environmental activists, including securing government funding, getting meetings with high-level officials and attending events.
http://dailycaller.com/2014/02/24/emails-another-top-epa-official-used-private-email-account-to-aid-environmentalists/
“What we found was that the magma has been stored beneath Mount Hood for at least 20,000 years–and probably more like 100,000 years,” Kent said.
At least he’s honest about the fuzziness of ‘paleo’-anything.
Michael Mann would probably have told us that the magma had been stored for 20,178 years…eight months 11 days 4 hoursand 23 minutes!
I was just reading about it at Erik Klemetti’s blog here:
http://www.wired.com/wiredscience/2014/02/ephemeral-nature-magma-prior-eruption/
Toward the end of his posting is a note about a potentially very dangerous caldera producing supervolcano that has been injecting new magma recently. It is Laguna del Maule in Chile and he posts a link to a previous article that is well worth reading. These things can apparently “go off” rather quickly.
Forget Mt. Hood, it’s Yellowstone and Long Valley calderas that matter the most. Maybe it’s time to do some soil sampling and lake bed sediment studies of past super eruptions reaching DC.
“What happens when they mix is what happens when you sqeeze a tube of tooth paste in the middle”…..”some comes out the top, but in the case of Mount Hood it doesn’t blow the mountain to pieces.”
Is this supposed to be science? In what way is the mixing of magmas analogous to toothpaste tubes….let alone squeezing them in the middle.
I’d like to test this hypothesis but I’m stuck here in North Queensland so if anyone is going past Mount Hood, would you give it a squeeze for me? (Preferably in the middle)
Think of all the cooling aerosols…
But …, wait a minute. Aren’t there people living close to dormant volcanoes…
This is actually somewhat scary.
I have read that Mt. Rainier (don’t remember sources) could blow with enough force to destroy not only Seattle, but possibly even Portland and Vancouver BC. A frightening prospect, indeed.
This is also a mostly dormant seismic area that has apparently produced magnitude 9 or even greater earthquakes (comparable to the New Madrid quakes in what is now Missouri’s “boot heel” that shook with sufficient force to kill people by slamming them to the ground).
It’s been only a matter of centuries since Earth has somewhere experienced a natural disaster on this scale. One wonders if we are overdue for another.
Mt Hood, and Mt Rainier are probably not to be worried about – likelihood of plenty of warning, all same Mt St Helens. But consider the (Yosemite?) (Yellowstone National Park?) which has been described as a supervolcano ready to blow at a moment’s notice. I saw one of those “Today be a bit worried, tomorrow the end of the world as we know it” TV films with the supervolcano ready to blow, doing so, and the cloud of ash crossing the USA to delete all life even as far as Washington DC (perhaps they had it in for politicians).
But also spare a prayer for Australia. Australia has been moving north for some 30 – 40 M years over a hot spot, leaving lava flows and mountains on the east coast from Queensland to the south. Where I live, Banora Point, is on the outer edge of one of the world’s largest calderas – I think it is about number 5 or 6, in diameter. It blew about 25 M years ago. Luckily for me, as Australia has moved north, the hot spot is now roughly under the southern edge of Port Philip – near Geelong – as if Geelong has not had enough to cope with with closures of factories, etc. Would make a mess of Melbourne and bung up the entrance to its port!
“It was the mixing of hot liquid lava with cooler solid magma that triggered Mount Hood’s last two eruptions about 220 and 1,500 years ago”
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OK, as a geologist, I have to nit pick.
Cooler solid magma ? By definition, magma is NOT a solid. I know they are trying to dumb this down for the general public, but that is technically incorrect. What they should have said was the cooler high viscosity magma – clearly this is what they meant from the rest of the article but not what they said
Currently active/erupting volcanoes list-
http://www.volcanodiscovery.com/erupting_volcanoes.html
The actual headline from the Reuters article:
Justices question Obama climate change regulations
Hi from Oz. Has anyone noticed that active volcanoes seem to erupt in cycles, and some seem to be in sync? Is there any research on this – for example whether these cycles are related to sunspot activity? Just askin…
Jeff L says:
February 24, 2014 at 3:18 pm”
Yep, when you look at Erik’s site (noted by Crosspatch above) there is much better analysis and comments (e.g. Boris Behnke) on what is going on. Pity that Reuters & co. think that “the masses” are so scientifically illiterate that they (er, we) need their dumbed-down explanations. On the other hand, maybe that’s why they expect us to swallow the CAGW lie….
Although Yellowstone and Long Valley are often mentioned, I’m more worried about Iceland, which has a couple of larger volcanos that are a tad overdue (Laki? and another…).
The cynic in me says grabs some marshmallows and a gas mask and hope for the best…..
The realist says “more data, more data, more data”…..
(The cynic in me can’t type very well, either….I meant grab some marshmallows…)
BoyfromTottenham,
Interesting observation you made. I mentioned to a family member following the tsunami that struck Fukushima that the east coast of japan was on or near the ring of fire and that we should get ready for more volcano/earthquake events around the pacific rim. My comment was off-hand and based on only common knowledge… not data.
I wonder if your idea about coincident volcano activity being from a common influence has merit.
But, but… volcanoes will save us from global warming.
http://www.ibtimes.com/global-warming-hiatus-caused-volcanoes-cooling-effect-study-says-eruptions-slow-global-temperature
Let it blow, let it blow, let it blow….
I must confess that I would be in awe of the spectacle of a huge volcanic eruption. Would love to see it. This all provided that nobody gets hurt, which is unlikely. Oh Well. I guess I’ll pass on it then.
This is almost as contradictory as an IPCC report.
They state the Magma has been solidified for thousands of years, then it has erupted twice in the last 1500 years the last time only 220 years ago?
Therefore the last time it was very molten was 220 years ago.
To talk about its age and the crystaline structure they would need a core sample from 4-5 Kms down. Good luck with finding a drill team.
One day some one will tell the real causes of what creates volcanoes, it lays in the same maths
used for the triggering of nuclear weapons. Harmonics, or as Willis would say numerology, but the bomb works.
Dudley Horscroft says:
February 24, 2014 at 2:42 pm
Luckily for me, as Australia has moved north, the hot spot is now roughly under the southern edge of Port Philip – near Geelong – as if Geelong has not had enough to cope with with closures of factories, etc. Would make a mess of Melbourne and bung up the entrance to its port!
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Not what one might call a real loss for the Sydney folk would it Dudley ! (lol)
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For the sake of our US friends and others there is an historical and on-going rivalry between Sydney and Melbourne that at times can become quite intense. The southerners are just jealous of Sydney Harbour even though they call the best-city-in-Australia people who live there hillbillies.
A few years back whilst walking through the Mount Warning national park in Queensland I noticed fragments of hexagonal basaltic columns pretty much identical to the famous Giant’s Causeway formations in Co Antrim. I wonder if they were produced during the same geological epoch?
I’ve got a list of about 10 things that “worry” me and neither volcanoes nor global warming make the list.
I live at the base of Mount Hood, in the small community of Welches. I work at Timberline Lodge, which is located at 6,000 feet, on the south side of Hood. Mount Hood is 11,245 feet in elevation, the highest lift, which rises to the top of the Palmer glacier, is 8, 540′. There are active fumaroles on the south side of the volcano, approximately one thousand feet below the summit. The wind frequently brings the smell of sulfur to the ski slopes.
The town of Government Camp (Govy) is located 3 miles below Timberline Lodge, at approximately 4,000′, or 6 miles from the summit. It is a typical alpine town, basically a drinking town with a skiing problem. There are more than a thousand people who live there, and in the immediate surroundings.
Everyone who lives on or near the volcano is aware of the dangers, and most have an evacuation plan, and or contingency plans for leaving quickly, or not so quickly, in the event of an impending eruption. Personally, I believe mud flows and lahars on the local rivers (Sandy river, Salmon river, Still Creek, Zig Zag river and Hood rivers, would be the larger dangers.
If Mount Hood was in winter coat, with billions upon billions of gallons of water locked up in snow, I think it would be catastrophic for all the communities in the Mount Hood watershed, including Portland.
Hope you enjoyed my bit of local Mount Hood culture.
Well what does it mean that a volcano goes from dormant to active very quickly ?
So it doesn’t erupt for thousands of years, and then it “potentially” does:…..”””””The time it takes to liquefy and potentially erupt, however, is surprisingly short–perhaps as little as a couple of months…..””””
No it seems like it takes thousands of years to potentially erupt. Now when it does erupt, it can do that in a few seconds in some cases; see Mt St Helens for example.
Now climate change causes dormant volcanoes to “potentially” erupt by WHAT physical process ?? Maybe an increase in atmospheric pressure due to the higher CO2 abundance ?
Not surprising at all considering that 25% of Americans don’t even know that Earth orbits the Sun.
http://www.livescience.com/43593-americans-ignorant-about-science.html
And for Walter Cooley, I never got erupted on, on Mt Hood while skiing in the early 1960s, but I have skied on Mt Ruapehu, in NZ, while its next door neighbor, Mt Ngauruhoe , was actively erupting. The ash falling on the Ruapehu snow, took the wax off the bottom of our skis. Well hell it also took the bottoms off our skis.
So we gave up the skiing in favor of going mountain climbing instead ; on Mt Ngauruhoe. Sort of a group entry in the Darwin awards. Somewhat awe inspiring to look up, and see rocks the size of houses, falling out of the sky around you. Well the safest place was the slightly cooled end of the lava flow, sort of forming an overhanging cliff to shield you from the rock houses. And the lava was nice and warm up there too.
But it was more fun to go swimming in the Ruapehu crater lake, which was a bit of a sulphuric acid solution, and bloody cold, except when you swam over a bubbling fumarole and hit the hot water, that singed your eyebrows.
Well the acid was hell on the woolen swim suits, so they only lasted a season.
goldminor on February 24, 2014 at 1:36
@ DS…I wonder if cooling would have the potential to increase volcanic and earthquake activity by causing crustal shrinkage?
Oh, crud, you might be right.
…quick, someone tell Gore that Global Warming is possibly saving the planet! (I am quite confident he will get right on that real scientific investigation)
A graphic of when the PNW volcanos have erupted in the last 4,000 years:
http://www.pnsn.org/volcanoes/cascades_eruptions_4000yrs.gif
Actually no, I haven’t noticed. Is there any evidence volcanoes erupt in cycles?
I’ve looked at earthquakes and time between events is very much an exponential distribution, suggesting random, independent and memoryless processes (except for aftershocks). And the frequency isn’t increasing. I would be surprised to find volcanoes behave otherwise.
Dodgy Geezer says:
February 24, 2014 at 1:40 pm
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Here’s the reversible relationship…
Harmless Volcano + CO2 => Volcanic Eruption
Volcanic Eruption + CO2 TAX => Harmless Volcano
Now will you believe me when I say we’re doomed?
I have read of some anecdotal evidence that an increase in subduction zone volcanic activity seems to happen in the decade(s) immediately following a megathrust quake but the problem is we have so few of those sorts of events, it’s hard to correlate. Last one in the Cascadia Subduction Zone was in January of 1700 and we only know that from matching up some on-site evidence with tsunami records from Japan (tsunamis arriving in Japan with no associated local quake). Notice the 2005 quake and the current seeming increase in volcanic activity now. Look to see what happens in Japan after about 2020. Maybe there is a link. But it would seem to reason that an injection of freshly subducted material would eventually feed these source areas for magma.
If you are going to worry about volcanoes, worry about the caldera under Yellowstone amongst others. If they any of them go it is game over, for everything.
george e. smith says:
February 24, 2014 at 5:35 pm
> So we gave up the skiing in favor of going mountain climbing instead ; on Mt Ngauruhoe. Sort of a group entry in the Darwin awards.
Congrats on failing to win!
One of the dumber things I did while walking into work at night during the New England Blizzard of ’78 was to take a shortcut through a fragment of an old orchard. The only light was from street lights I couldn’t see. I could make out the shape of the next row of apple trees, but I couldn’t see the drifts I was walking through. One step would be in snow up to my waist, the next could be into windswept bare ground. Had I lost my bearings it would have been bad news, I think I checked my track and realized it was filling in quickly. Had power gone out to the neighborhood, that would have been very, very bad. When I walked home I stuck to the roads.
Truthseeker says:
February 24, 2014 at 6:28 pm
The USGS isn’t too concerned. I can still find a document I read years ago.
The report reffed at http://pubs.usgs.gov/of/2007/1071/ says in small part about the caldera forming eruptions:
Although the probability of a large caldera-forming eruption at Yellowstone is exceedingly small, it is exceedingly difficullt to make a defensible quantitative estimate of that probability. As there have been three such eruptions in about the past 2,100,000 years, there are only two intereruptive periods from which to gauge any additional possible interval between the third and a potential fourth such event. The first interval, between the Huckleberry Ridge (2.059±0.004 Ma) and Mesa Falls (1.285±0.004 Ma) caldera-forming events, was 774,000±5700 years. The second interval, between the Mesa Falls and Lava Creek (0.639±0.002 Ma) events, was 646,000±4400 years. A statement, widely repeated in popular media, regards such eruptions as occurring at Yellowstone “every 600,000 years” with the latest eruption having been “600,000 years ago”. This is commonly taken to imply that another such eruption is “overdue”. Such a statement is statistically indefensible on the basis of the extrapolation of two intervals. (Even the simple arithmetic average of the two intervals is 710,000 years, not 600,000 years). From the line of reasoning outlined here, the probability of a fourth large caldera-forming event at Yellowstone can be considered to be less than 1 in a million, below the threshold of hazards interest unless future premonitory phenomena, probably more severe than those recorded historically in caldera systems around the world (Newhall and Dzurisin, 1988), were to be recognized.
Personally, I have Rainier on the top of my lower 48 concerns. Too close to too many people and with plenty of ice to help form a lahar – just like it’s done many times in the past.
Good essay, Anthony. Who knows whether they are trying to rally the base, or whatever. It’s very hard to pitch global warming when the temperature over a substantial chunk of the country is recorded with a minus sign in front of it. I lately work “global warming” into just about every discussion I have these days, and all it elicits is scornful ripostes, comments about Al Gore, and so on. And this is from doctors, engineers, what have you. Naomi, unfortunately, is as stupid as she is ugly, and a loser on many other fronts. One has to pity her wasted life – and those who have to deal with her.
Pedantic old Fart says:
February 24, 2014 at 2:16 pm
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That is known as using an analogy.
I looked up the New Madrid Quake to refresh my thoughts. I notice that the quake occurred in the middle of the Dalton Minimum. Perhaps I have just answered my own question, which I had posed earlier?
Well…. Clearly is it time for a Magma Cap and Trade Scheme. Lets admit that EVERYBODY is walking around on top of some magma someplace. Sure, it might be many miles below you, BUT it could be just under your feet. And we have to limit all this walking around on Magma stuff, surely for the children. If you disturb the Magma it might get angry…… OH NOES…..
Just pony up and pay your “Ambulating On Top Of The Magma TAX (AOTOTMT)” and your friendly government will do the rest and come up with some sure fire technology to replace all that dangerous magma with “renewable bedrock” ™.
Do I really need a “sarc off” tag ????
Cheers, Kevin.
There will be plenty of notice if Yellowstone should “decide” to erupt.
The upwelling of magma will lift the surface around the magma chamber.
Monitoring surface elevation is standard practice around potentially dangerous volcanoes.
So there will be plenty of warning but the effect will still be devastating, particularly for North America.
The last “super volcano” to erupt was probably Toba in Sumatra, Indonesia about 70,000 – 75,000 years ago. One of the effects of that event was to reduce the world wide modern human population to around 5,000 as well as killing off most of our cousins/competitors through Asia.
There is more. Another sizeable quake of 6.3 hit in 1895. That would coincide with the cooling period prior to the warming between 1914/15 till 1946/47 approx. There is also a large event listed as occurring around 1450, this would be another quake striking close to the Sporer grand minimum. There is a recorded event from explorers on dec 25 1699. This would be close to the end of the Maunder Minimum. It would seem that the New Madrid Fault bears watching. Especially due to the fact that many of us have been discussing the likelihood of another gm in the not too distant future. I have noticred the upswing in quakes around Missouri started around 3 years ago, when I became interested in following quakes due to the Great Tohuko Quake of 2011. In the last week and especially yesterday, there were multiple strikes in Missouri. Another possible connection is what I thought looked to be a correlation with movements on the Oulu neutron monitor. The Oulu has been showing a fall in the scale over the last week. Several months back, when I had first noted a possible correlation I had also made a forecast that the scale would show a drop by as early as March of this year. Dr Norman Page seemed to think that I was onto something also. As a disclaimer, I admit that I know very little about aspects or connections with what drives the changes with the neutron flow. Yet sometimes I seem to have an odd ability to point and say ‘what is that and why does it seem to be doing this?’. Also, the neutron monitor would still have to show a sharp drop from where it now stands at this time to get within the range of having an effect on either volcanic activity or quake activity. This is completely speculative.
Another thought. Although I had initially been wondering if cooling could have an affect, what if the connection is changes in the geomagnetic fields due to solar shifts? I have heard it posited here on solar discussions that a gm leads to increased solar influence which would then drive down the gcr flow. Is that the connection between sharp drops on the Oulu monitor potentially corresponding with some major Earth events?
And then there’s the unstudied interaction with our planets core and the cyclical phase swapping (650, 000 to 900,000 year) of polarity and our stars output patterns.
Then again, the planetary core delta temperature/pressure over a small geological period of time may also incorporate the ingestion of solar influences on the geological timeframe… The IMF and our location are certainly key to cyclical events…
When the polarity change begins again, so does death and life, seeing the loss of magnetospheric protection allows only the subsurface and ocean dwelling organisms a chance to move on.
“””””…..Ric Werme says:
February 24, 2014 at 6:28 pm
george e. smith says:
February 24, 2014 at 5:35 pm
> So we gave up the skiing in favor of going mountain climbing instead ; on Mt Ngauruhoe. Sort of a group entry in the Darwin awards.
Congrats on failing to win!…….”””””
Well I appreciate that Ric. I actually have three bona fide solo entries in that award contest; one by fire, and one by ice, and one by failed (avoided) human powered flight, The latter occurred on that very same Mt Ruapehu, while skiing across a half mile long traverse across a face tilted at about 45 degrees; not realizing that the bottom edge of the face was a 500 ft cliff back down to the loading point of the chair lift. In the middle of a turn, straight down the fall line, I suddenly wondered what would happen if I fell over; about then is where sheer panic took over, and guided me out the other end. So they called this place “The high traverse”, and my skiing companions pointed it out to me when we were finally back at the ski lift. They were good skiers; I was a klutz.
The icecapade involved a late night stroll down the Rock river, in Janesville Wisconsin in late winter; that was down the middle of the river, on the crunchy snow. I found out next morning after the rain, that the ice did NOT run all the way to the bank, at the back lawn of my motel.
And I launched my career of self imposed insanity, by running through the middle of a Guy Fawkes night bonfire, and fell over, by stepping into the empty goal post hole. That’s how I want to go out; in style, like Siegfried.
My father and brother were skiing in an unfamiliar area, I think in France, and checked out one possible way down but decided it wouldn’t work out and took the gentler way. When they reached the bottom they looked back up and realized they had skied onto a cornice over a cliff edge. Definitely not the right way down….
Ric Werme, thank you for putting my mind at ease. All other volcanoes are largely local disasters, not global ones. So, the volcano lesson for today is … don’t worry, be happy.
Here you you go, chaps. Amuse yourselves with a little light reading about genetic bottlenecks.
It’s only Wikipedia, although some for the references are useful!!
http://en.wikipedia.org/wiki/Toba_catastrophe_theory
http://phys.org/news/2013-05-volcanic-winter-toba-super-eruption.html
http://www.geo.mtu.edu/~raman/papers/RoseTobaFallGeology.pdf
Ric Werme says:
February 24, 2014 at 6:55 pm
The USGS isn’t too concerned. I can still find a document I read years ago.
The report reffed at http://pubs.usgs.gov/of/2007/1071/ says in small part about the caldera forming eruptions:
“From the line of reasoning outlined here, the probability of a fourth large caldera-forming event at Yellowstone can be considered to be less than 1 in a million,”
Actually I think the USGS may have slipped up here. If the supervolcano has erupted three times in the past, with gaps of very roughly 774 000 and 646 000 years between them, I think there is a reasonable supposition that there could be another eruption within 1M years after the last eruption – other things being equal. Put what level you may like on a “reasonable supposition” but I would suggest at least 1:2. I think that the USGS would have been right if they had stated:
“the probability of a fourth large caldera-forming event at Yellowstone WITHIN THE NEXT 10 YEARS can be considered to be less than 1 in a million,”
“For Mount Hood, the threshold seems to be about 750 degrees (C)–if it warms up just 50 to 75 degrees above that, it greatly decreases the viscosity of the magma and makes it easier to mobilize.”
Yeh, the melting point of the rock. I’m sorry but this is another load of wishful thinking. How have the measured the age of the magma? How have they shown that it just sits there for 10s of thousands of years. This looks like an attempt to get some funding for more measuring stations
One thing I don’t see them mentioning in this report is the importance of water content. Perhaps it is counter intuitive to realise that magma as hot rock can contain large amounts of water until you see it being released as steam during an eruption. The presence of extra water can change the chemical properties, and therefore the physical properties of magma. Maybe what they have been measuring is not just due to the increase in temperature caused by new magma, but an increase in water content.
Poas Volcano Erupts In Costa Rica
http://weaselzippers.us/176576-poas-volcano-erupts-in-costa-rica/