Earthquake models get a big shakeup with clues buried in the San Andreas fault

The keys to understanding those earthquakes may lie within the fault’s danger zone, inside the glass walls of a nondescript office building in Menlo Park, a suburb on San Francisco’s peninsula. There lies the regional office of the US Geological Survey, the keepers of earthquake hazard data. Thanks in part to geologists working in that building, this fault is one of the best-studied on the planet. Their simulation showed something surprising. “At least if the models are to be believed, much of the mountain-building could actually happen between earthquakes rather than during the earthquakes themselves,” says Hiller.

In most faults, moving tectonic plates try to force themselves past each other. For years or decades or even centuries, they’ll quietly keep pushing, building up energy at the boundary.

Inevitably, something snaps. All that energy gets released in an abrupt tremor: an earthquake. But between quakes, that energy could go into building mountains, too, according to these simulations.