Big Bangs: 'Stirring' Secrets Of Deadly Supervolcanoes Uncovered

Science Daily ^ | 5-30-2008 | McGill University

[blam]

Big Bangs: 'Stirring' Secrets Of Deadly Supervolcanoes Uncovered

Supervolcanoes are orders of magnitude greater than any volcanic eruption in historic times. They are capable of causing long-lasting change to weather, threatening the extinction of species, and covering huge areas with lava and ash. (Credit: iStockphoto/Koch Valérie)

ScienceDaily (May 30, 2008) — Researchers from McGill University and the University of British Columbia (UBC) have simulated in the lab the process that can turn ordinary volcanic eruptions into so-called “supervolcanoes,” with potentially devastating worldwide impact.

The study was conducted by Dr. Ben Kennedy and and Dr. Mark Jellinek of UBC’s Department of Earth and Ocean Sciences, and Dr. John Stix, chair of McGill University’s Department of Earth and Planetary Sciences. Their results were published May 25 in the journal Nature Geoscience.

Supervolcanoes are orders of magnitude greater than any volcanic eruption in historic times. They are capable of causing long-lasting change to weather, threatening the extinction of species, and covering huge areas with lava and ash.

Using volcanic models made of plexiglass filled with corn syrup, the researchers simulated how magma in a volcano’s magma chamber might behave if the roof of the chamber caved in during an eruption.

“The magma was being stirred by the roof falling into the magma chamber,” Stix explained. “This causes lots of complicated flow effects that are unique to a supervolcano eruption.”

“There is currently no way to predict a supervolcano eruption,” said Kennedy, a post-doctoral fellow at UBC. “But this new information explains for the first time what happens inside a magma chamber as the roof caves in, and provides insights that could be useful when making hazard maps of such an eruption.”

The eruption of Mount Tambora in Indonesia in 1815 – the only known supervolcano eruption in modern history – was 10 times more powerful than Krakatoa and more than 100 times more powerful than Vesuvius or Mount St. Helens. It caused more than 100,000 deaths in Indonesia alone, and blew a column of ash about 70 kilometres into the atmosphere. The resulting disruptions of the planet’s climate led 1816 to be christened “the year without summer.”

“And this was a small supervolcano,” said Stix. “A really big one could create the equivalent of a global nuclear winter. There would be devastation for many hundreds of kilometres near the eruption and there would be would be global crop failures because of the ash falling from the sky, and even more important, because of the rapid cooling of the climate.”

There are potential supervolcano sites all over the world, most famously under Yellowstone National Park in Wyoming, the setting of the 2005 BBC/Discovery Channel docudrama Supervolcano, which imagined an almost-total collapse of the world economy following an eruption.

Adapted from materials provided by McGill University.

[VanShuyten]

I’ve seen those reports, and I’ve tried to reconcile them with temperature data from Greenland ice cores. Although there is a drop in temperature at the point of increased sulfur deposits from Toba, the temp graph of the last ice age looks very similar to the temp graph of the one just before that. Perhaps the drop in temperature and rebound to the “normal” rate of change was so rapid that it doesn’t show up well in the ice cores. A volcanic winter lasting a few centuries, or even just a few decades, might have been long enough to create the human bottleneck, but not long enough to have altered the general climate trend nor have shown up in the core samples.

[21twelve]

“Using volcanic models made of plexiglass filled with corn syrup”

I wonder if they ended up looking like Marsha(?) Brady after the experiment?

[djf]

The climate guesstimates I heard were all based on O16-O18 ratio in microfauna from sea floor sediments.

How well that correlates to other data we will never be sure, but the truth is probably somewhere in the middle.

Toba was a monster event.

http://volcano.und.edu/vwdocs/volc_images/southeast_asia/indonesia/toba.html