Earthquakes Could Trigger Massive Supervolcano Eruptions, Study Suggests

In Yellowstone National Park, the rim of a supervolcano caldera is visible in the distance. Credit: National Park Service Enlarge

Supervolcanoes, such as the one dormant under Yellowstone National Park, may erupt when cracks form in the roofs of the chambers holding their molten rock, according to a new study.

If scientists want to monitor supervolcanoes to see which ones are likely to erupt, this finding suggests they should look for telltale signs, such as earthquakes and other factors that might crack the magma chambers of these giant volcanoes.

Supervolcanoes are capable of eruptions overshadowing anything in recorded human history — ones in the past could spew more than 500 times more magma and ash than Mount St. Helens did in 1980, the researchers said. These massive eruptions would also leave behind giant craters known as calderas that measure up to 60 miles (100 kilometers) wide. Twenty or so supervolcanoes exist today, including one beneath Yellowstone in the United States. [Big Blasts: History’s 10 Most Destructive Volcanoes]

Much remains unknown about what triggers supervolcano eruptionsbecause no supervolcano has been active since the earliest human records began. Conventional volcanoes are known to erupt as molten rock flows into and pressurizes their magma chambers. However, previous research suggested this kind of trigger does not work for supervolcanoes, whose magma chambers can be dozens of miles wide and several miles thick — magma cannot fill these chambers fast enough to generate enough pressure for an eruption.

“Supereruptions are very rare because they are very difficult to trigger,” study lead author Patricia Gregg, a volcanologist at the University of Illinois at Urbana-Champaign, told Live Science. “Part of what makes supereruptions so intriguing is that they are so infrequent. This indicates that there must be something different about supervolcano evolution and eruption versus smaller volcanoes that erupt more frequently.”

Scientists recently suggested that supervolcanic eruptions occur because magma might be less dense than the rock surrounding it. This could force magma to buoy up through the ground, the way a balloon floats upward in water, potentially pressurizing magma chambers enough for eruptions.

However, at supervolcano sites, “we don’t see a lot of evidence for pressurization,” Gregg said in a statement. When she and her colleagues incorporated magma buoyancy into their numerical models of supervolcanoes, they found it could not trigger eruptions.

“We have ruled out a potential triggering mechanism for supereruptions,” Gregg said. “This is particularly important when investigating unrest at a supervolcano. If all it takes is buoyancy to trigger a catastrophic caldera-forming eruption, we should be very concerned when we see images of the large magmatic systems at Yellowstone and Toba, Indonesia, for example. However, through rigorous testing, we have found no link between buoyancy and the potential to erupt one of these systems. Buoyancy just does not produce a force strong enough to do it.”

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