A new study has found that the Yellowstone supervolcano contains more magma
Volcanologists identify magma reservoirs by monitoring earthquakes. Seismic waves travel through the Earth’s interior before being detected by surface seismometers. They move more slowly through hot and partially molten rock, and scientists use their travel time to interpret how molten parts of the subsurface are.
But this traditional seismic imaging technique is imperfect. Seismic waves sometimes bend around melt pockets. This method also assumes that seismic waves travel in a simplified manner, from the earthquake directly to the seismometer; in reality, seismic waves radiate in all directions and critical information about the Earth’s subsurface is lost.
For the new study, the authors turned to a 20-year record of Yellowstone’s background seismic noise — generated by distant ocean waves, wind and human activity — to focus on the volcano’s overlooked melting. They abandoned traditional seismic simplifications and used supercomputers to more accurately represent the travel of seismic waves.
The team found that the seismic waves slowed to a crawl when they traveled 2 miles to 5 miles down—corresponding to the upper segment of what is believed to be the Yellowstone Volcano’s shallower magma reservoir. This suggests that up to 20 percent of this entire reservoir is molten.
Fortunately, it’s not something to lose sleep over. A rule of thumb is that reservoirs can’t trigger eruptions without being 35 percent to 50 percent molten, when things are “kind of like a crystal soup,” said Ross Maguire, a seismologist at the University of Illinois at Urbana-Champaign and a study author. This value, which volcanologists often debate, is likely to vary between volcanoes. Nevertheless, Yellowstone’s 20 percent is “still well below that critical threshold,” Dr. Maguire said.
For those hoping to unlock the secrets of other volcanoes, this study confirms that this relatively new technique “is a really good way to go,” said Diana Roman, a geophysicist at the Carnegie Institution for Science in Washington, D.C., who was not involved in the study. the survey.
“It’s a bit like getting a new lens on an old camera,” Dr Poland said. “It’s the same camera, but now you have better resolution. You see more clearly.