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Supervolcano eruptions are preceded by clear warning signs

A study led by researchers at the University of Illinois has found that there are clear geological signs that provide ample warning before a supervolcano eruption. Models developed by the team could help inform authorities of what to expect before the explosion of a supervolcano.

“Traditionally, it is thought that eruptions occur when the pressure caused by hot magma overtakes the strength of a volcano’s roof rock,” said study co-author Professor Patricia Gregg. “But super volcanoes tend to occur in areas of significant tectonic stress, where plates are moving toward, past or away from each other. That plate motion will affect model calculations.”

Professor Gregg teamed up with graduate student Haley Cabaniss and fellow Geology Professor Eric Grosfils to create a model of regional-scale tectonic stress based on the Taupo Volcanic Zone in northern New Zealand. They discovered that any type of tectonic stress impacts the stability of supervolcanoes.

“It does not matter if it is extensional, compressional or shear stress,” said Cabaniss. “Any tectonic stress will help destabilize rock and trigger eruptions, just on slightly different timescales. The remarkable thing we found is that the timing seems to depend not only on tectonic stress, but also on whether magma is being actively supplied to the volcano.”

The team analyzed conditions with different amounts of magma supply, stress, and tectonic plate movement. With any given scenario, magma chambers remained stable for hundreds to thousands of years while new magma was being supplied to the reservoir.

“We were initially surprised by this very short timeframe of hundreds to thousands of years,” said Professor Gregg. “But it is important to realize that supervolcanoes can lay dormant for a very long time, sometimes a million years or more. In other words, they may remain stable, doing almost nothing for 999,000 years, then start a period of rejuvenation leading to a large-scale eruption.”

The results of the study suggest that geological evidence to warn of an impending eruption will occur far in advance of a catastrophic event and will be unmistakable.

“When new magma starts to rejuvenate a supervolcano system, we can expect to see massive uplift, faulting and earthquake activity,” said Professor Gregg. “Far greater than the meter-scale events we have seen in recent time. We are talking on the range of tens to hundreds of meters of uplift. Even then, our models predict that the system would inflate for hundreds to thousands of years before we witness catastrophic eruption.”

“People need to keep in mind that sites like Yellowstone are very well-monitored,” said Cabaniss. “It is also important to note that our research suggests that the whole rejuvenation-to-eruption process will take place over several or more human lifetimes. Our models indicate that there should be plenty of warning.”

The study is published in the journal Geophysical Research Letters.

By Chrissy Sexton, Staff Writer

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