What Triggers a Supervolcano: Outside Environmental Factors May Cause Massive Eruption

First Posted: Nov 05, 2015 02:46 PM EST

What causes a supervolcano to finally blow its top? Scientists have taken a closer look at these features, and have found that these massive magma chambers may erupt when the roof above them cracks or collapses due to external triggers.

Learning triggering mechanisms for supervolcanoes is crucial for monitoring supervolcano systems, including the one that lies beneath Yellowstone National Park.

"If we want to monitor supervolcanoes to determine if one is progressing toward eruption, we need better understanding of what triggers a supereruption," said Patricia Gregg, one of the researchers, in a news release. "It's very likely that supereruptions must be triggered by an external mechanism and not an internal mechanism, which makes them very different from the typical, smaller volcanoes that we monitor."

A supervolcano is classed as more than 500 cubic kilometers of erupted magma volumes. For comparison, St. Helen's ejected just one cubic kilometer of material. This means that supervolcanoes could potentially wreak havoc on our planet's ecosystem.

Using numerical models, the researchers looked at what might trigger a supervolcano. They found that even when the chamber was huge, buoyancy added very little pressure to the system. Instead, something would have to happen to the roof above the magma chamber before it erupted.

"If we see a correlation between magma chamber size and the ability to erupt, it is important to know if supervolcano eruptions are triggered by internal factors or by foundering and faulting in the roof," said Gregg. "It may mean that we have to monitor these volcanoes differently. If the trigger is an external force, whether it be an earthquake or a fault, then we should look at seismicity, what types of faults are being developed, what is the stability of the roof, and what kinds of activities are happening on the surface that could cause faulting."

The findings are published in the Journal of Volcanology and Geothermal Research.

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