The new issue of Seismological Research Letters has come to my door. These journals are the only contact I have left behind the 'paywall'. This year's conference is in Kingston, but I don't really have the mood to see everybody. (They don't really think much of my blog!).
This is what you call a typical 'big author list' paper! It was a massive effort, involving the deployment and constant shifting of a large number of seismometers. Basically, they leave the seismometers at a bunch of spots for a while, and then calculate the seismic velocities of the ground beneath them. They did this for all of the western US. Then they get a map like this.
The reds are warm, soft areas with low seismic velocities. This is usually due to volcanic heating, or a thin crust. The blues are cold crust, which may be due to the subduction of a cold oceanic slab, or ancient, thick crust.
The cross-sections are interesting.
Section A goes through the Seattle subduction zone, and you can see the big slab driving down. Section D shows the Yellowstone hotspot. And so on.