Scientists from the University of Utah have made a
hot, new discovery:
The new report fills in a missing link of the system. It describes a large reservoir of hot rock, mostly solid but with some melted rock in the mix, that lies beneath a shallow, already-documented magma chamber. The newly discovered reservoir is 4.5 times larger than the chamber above it. There's enough magma there to fill the Grand Canyon. The reservoir is on top of a long plume of magma that emerges from deep within the Earth's mantle.
Enough to fill the Grand Canyon! Nonetheless, still
no need to panic about a supervolcano eruption:
The discovery does not, on its own, increase the chance of an eruption, which is driven by an emptying of the shallow chamber. The last major eruption was 640,000 years ago, and today the threat of earthquakes is far more likely. But the deeper chamber does mean that the shallow chamber can be replenished again and again. “Knowing that you have this additional reservoir tells you you could have a much bigger volume erupt over a relatively short time scale,” says co-author Victor Tsai, a geophysicist at the California Institute of Technology in Pasadena. The discovery, reported online today in Science, also confirms a long-suspected model for some volcanoes, in which a deep chamber of melted basalt, a dense iron- and magnesium-rich rock, feeds a shallower chamber containing a melted, lighter silicon-rich rock called a rhyolite.
See the computer model created by the University of Utah and the description of the new magma reservoirs below:
This animation shows the underground volcanic plumbing system beneath the Yellowstone supervolcano in Wyoming, as revealed by a new University of Utah seismic imaging study. The green lines represent the boundary of Yellowstone National Park. The study focused on Earth's crust, shows the previously known magma chamber (orange) about 3 to 9 miles beneath the surface, and reveals a previously unknown magma reservoir (red) at a depth of 12 to 28 miles. Beneath that is the Yellowstone hotspot plume (yellow) which brings hot rock up from deep within Earth's mantle. The new study, published online in the journal Science on April 23, 2015, did not focus on the mantle and thus image of the plume has poor resolution and is distorted from what previous imaging studies showed. The black lines show, first, the boundary of the giant volcanic crater or caldera that exploded during Yellowstone's last supervolcano eruption 640,000 years ago and, second, the outlines of what are called resurgent domes within the caldera. The white dots are locations of earthquakes that were used in the study.