Interpreted model of seismic wave speeds at Mount St. Helens with p...

Graphic shows an east to west cut-away of Mount St. Helens with an interpreted model of seismic wave speeds under the volcano and earthquakes from 2008-2016. The colors of the model represent changes in seismic p-wave velocities from tomographic studies (Waite and Moran, 2009; doi:10.1016/j.jvolgeores.2009.02.009). Cooler colors represent faster regions; redder colors are slower velocities. The red outline beneath the volcano represents the authors' interpretation of the most likely location of the magma plumbing system.

Open circles are well-located earthquakes from February 1, 2008 to November 19, 2016. The filled circles are earthquakes from November 19-29, 2016. Earthquake locations courtesy of the Pacific Northwest Seismic Network.

Note that the model and outline of the magma plumbing system are slightly offset from the earthquake locations due to the perspective provided in this graphic.