To make a story short, a handful of geologists have speculated, at least since the late 1980s, that the San Andreas Fault could actually be dying out over time—that the San Andreas is jammed up in a place called the “Big Bend,” near the town of Frazier Park, and that it is thus losing its capacity for large earthquakes.

As a result, all of that unreleased seismic strain has to go somewhere, and there is growing evidence—paleoseismic data, LiDAR surveys, GPS geodesy—that the pent-up strain has been migrating deep inland, looking for a new place to break.

That new route—bypassing the San Andreas Fault altogether—is the Walker Lane (and its southern continuation into the Mojave Desert, known as the Eastern California Shear Zone).