The uncertainty of science: Geologists have determined that the magma reservoir under Yellowstone is much bigger than previously thought.
Jamie Farrell, a postdoctoral researcher at the University of Utah, mapped the underlying magma reservoir by analysing data from more than 4,500 earthquakes. Seismic waves travel more slowly through molten rock than through solid rock, and seismometers can detect those changes.
The images show that the reservoir resembles a 4,000-cubic-kilometre underground sponge, with 6–8% of it filled with molten rock. It underlies most of the Yellowstone caldera and extends a little beyond it to the northeast.
The geologists also noted that the threat from a huge volcanic eruption is less of a concern than that of earthquakes.