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New Study Suggests We Don't Understand Supervolcanoes (sciencealert.com)
Better microsampling (and analysis) are revealing "previously obscured" clues about how super-hot molten lava behaves, according to a Science Alert article shared by schwit1:
"The older view is that there's a long period with a big tank of molten rock in the crust," says geoscientist Nathan Andersen from the University of Wisconsin-Madison. "A new view is that magma is stored for a long period in a state that is locked, cool, crystalline, and unable to produce an eruption. That dormant system would need a huge infusion of heat to erupt." Such a huge infusion of heat is what's thought to have unleashed a violent supereruption in California some 765,000 years ago... [A]s awesomely destructive as the supereruption was, lingering evidence from the aftermath can tell us about the magma conditions deep underground before the top blew so spectacularly.
Specifically, an analysis of argon isotopes contained in crystals from the Bishop Tuff -- the large rocky outcrop produced when the Long Valley Caldera was created -- shows the magma from the supereruption was heated rapidly, not slowly simmered. Geologically speaking, that is -- meaning the heating forces that produced the supereruption occurred over decades, or perhaps a couple of centuries. (A long time for people, sure, but a blink of an eye in the life-time of a supervolcano.) The reasoning is that argon quickly escapes from hot crystals, so it wouldn't have a chance to accumulate in the rock if the rock were super-heated for a long time... Unfortunately, while scientists are doing everything they can to read the signs of volcanic supereruptions -- something NASA views as more dangerous than asteroid strikes -- the reality is, the new findings don't bring us any closer to seeing the future.
"This does not point to prediction in any concrete way," warns geologist Brad Singer, "but it does point to the fact that we don't understand what is going on in these systems, in the period of 10 to 1,000 years that precedes a large eruption."
Specifically, an analysis of argon isotopes contained in crystals from the Bishop Tuff -- the large rocky outcrop produced when the Long Valley Caldera was created -- shows the magma from the supereruption was heated rapidly, not slowly simmered. Geologically speaking, that is -- meaning the heating forces that produced the supereruption occurred over decades, or perhaps a couple of centuries. (A long time for people, sure, but a blink of an eye in the life-time of a supervolcano.) The reasoning is that argon quickly escapes from hot crystals, so it wouldn't have a chance to accumulate in the rock if the rock were super-heated for a long time... Unfortunately, while scientists are doing everything they can to read the signs of volcanic supereruptions -- something NASA views as more dangerous than asteroid strikes -- the reality is, the new findings don't bring us any closer to seeing the future.
"This does not point to prediction in any concrete way," warns geologist Brad Singer, "but it does point to the fact that we don't understand what is going on in these systems, in the period of 10 to 1,000 years that precedes a large eruption."
Any process which has a form of relaxation oscillations, such as mounting mechanical tension resulting in catastrophic release in an earthquake, or supernova blast in a binary star system, or an supervolcano eruption caused by a sudden event, has to have three underlying processes: first, of slow rise to criticality, second, of constant dissipation which pushes system away from criticality, and the third: of sudden relaxation when level of criticality is crossed.
Looking at the Earth geology, we first must understand at what rate it produces (and accumulates) heat internally, and at what rate it releases its internal heat. It may as well be that Earth is cooling faster then it heats itself, in which case, there as well could never be another supervolcano eruption. Or, it heats itself at rate slower than the rate it had 700k years ago, which would mean that another supervolcano eruption would be postponed much further into the future than simple linear interpolation would suggest. Or, perhaps greenhouse effect affects not only heat our planet receives by Sun's irradiation, but also the total rate of natural cooling of Earth as a whole, in which case we stand to lose much more than just ice caps and bad weather.