California’s supervolcano is dormant, but scientists say it’s turbulent: ScienceAlert

A new study conducted by researchers at the California Institute of Technology (CIT) suggests. Long Valley Caldera In eastern California it tosses and turns relentlessly as the deep magma chamber cools for a long, long sleep.

The last time the volcano erupted was Nearly 100,000 years ago. Long before that, enough ash was ejected to bury the modern city of Los Angeles under a kilometer of sediment.

Today, Long Valley Volcano is in a relatively sluggish state. But things are not calm on California’s eastern front. In the late 1970s, a swarm of earthquakes began launching from the caldera – Depression Which is located above the buried volcano.

For decades afterward, the volcano produced regular periods of “apparent disturbances,” which caused the ground to swell and deflate.

Fortunately, this is not necessarily a sign of impending doom. Researchers at CIT have now found evidence that all this disturbing activity is due to the supervolcano cooling, not heating.

“We don’t think the region is preparing for another massive volcanic eruption, but the cooling process may release enough gas and liquid to cause earthquakes and small explosions.” He says Geophysicist Zhongwen Zhan.

“For example, in May 1980, four magnitude 6 earthquakes occurred in the area alone.”

The team’s findings are based on data collected from a 100-kilometre-long fiber optic cable, using distributed acoustic sensing.

Over the course of a year and a half, researchers at Caltech used this interconnected system—the equivalent of 10,000 individual seismometers—to catalog more than 2,000 seismic events, many of which could not have been felt by humans on Earth.

This data was then plugged into a machine learning algorithm, which turned the measurements into a high-resolution map of the caldera and the volcano that lies beneath it.

This is the first time a network of deeply distributed acoustic sensors has revealed the Earth’s internal dynamics, says Ettore Biondi, a seismologist from Caltech and first author of the study.

the pictures produced The team says that these objects have “exceptional lateral resolution” at depths of up to 8 kilometers. Even images of the deeper parts, up to 30 kilometers deep, were captured with an “amazing level of detail.”

The results show a clear disconnect between the volcano’s large magma chamber, located 12 kilometers below the surface, and the shallow hydrothermal system located above it.

It appears that as the deep chamber cools, gases and liquids rise toward the surface, potentially causing earthquakes and swelling of the Earth.

This boiling effect could “stimulate marked surface deformation and earthquakes,” the researchers said. He writes.

This is different and much less dangerous than what happens during an active volcanic eruption when magma in a volcanic chamber pushes itself into the upper crust and out into the world.

The way seismic activity travels through these layers suggests that the top of the magma chamber contains a solidified cap of crystallized rock, which cools over time.

With the end of the supervolcano’s activity, researchers say He says His “beating heart” gradually slows down.

The team plans to measure those last pulses at a depth of 20 km using a 200 km cable of seismic sensors.

The study was published in Advancement of science.