A California supervolcano may have up to 240 cubic miles of magma below its surface, researchers reported in a new study.
The Long Valley Caldera had a major eruption 760,000 years ago, but scientists don’t think that will repeat itself any time soon, Newsweek reported. Most of the magma is not molten, but enough of it is that a normal-sized eruption could be possible at some future point.
The supervolcano has been dormant for 100,000 years, the researchers said.
“I imagine there could be smaller eruptions and indeed they are the most likely,” University of Cambridge geologist Robert White told New Scientist. “But there hasn’t been anything for a very long time.”
Gradual uplift at the center of Long Valley Caldera has sparked interest in recent years, but this is the first study to show what may lie beneath it, Newsweek reported. While small features were closer to the surface and larger ones were deeper underground, scientists weren’t really able to see the midcrust zone well until this study.
A team led by study author Ashton Flinders of the U.S. Geological Survey used seismic data collected over 26 years to create a 3-D image of the rocks and found that a huge magma deposit is likely in that previously shadowy region, New Scientist reported.
In another recent study, scientists found Wyoming’s Yellowstone supervolcano may have been formed when a massive slab of oceanic crust fractured beneath that part of North America, rather than because of magma coming up through cracks in Earth’s crust that already existed, Newsweek pointed out.