Fan-Chi Lin, professor of geology and geophysics, holds a portable seismometer. His team deploys hundreds of these instruments in the field to create images of underground formations and other subsurface features. Photo credit: Brian Maffly
That changed this week with new research by seismologists from the University of Utah and the University of New Mexico (UNM) who used hundreds of portable seismometers and a mechanical vibration source to render 2D seismic reflection images of the ground beneath Yellowstone’s caldera.
Using artificial seismic waves, the team determined that the top of the chamber is 3.8 kilometers, or about 12,500 feet, below Earth’s surface, and it is sharply delineated from the rock strata above, according to findings published in the journal Nature. The researchers also determined the portion of the uppermost magma chamber that is comprised of volatile gases and liquids.
“The depth of 3.8 kilometers is important,” said coauthor Jamie Farrell, a U research associate professor of geology and geophysics and chief seismologist for the Yellowstone Volcano Observatory, operated by the U.S. Geological Survey. “We know what pressures are going to be and how bubbles are going to come out of the magma. One thing that makes these eruptions so devastating is that if gases are trapped, they become very explosive as they decompress.”
The good news is that these findings indicate the long-dormant Yellowstone Volcano is in no immediate danger of eruption.
This is because much of the volatile gas released from the magma escapes through Yellowstone’s surface geothermal features, such as Mud Volcano, without accumulating to dangerous levels, according to coauthor Fan-Chi Lin, professor in Utah’s Department of Geology & Geophysics.
“When the magma rises from the deeper crust, volatile materials such as CO2 and H2O exsolve from the melt. Due to their buoyancy, they tend to accumulate at the top of the magma chamber,” he said. “But if there’s a channel, they can escape to the surface.”
Read the full article by Brian Maffly in @ TheU.
