Study Finds 'Large-Scale' Vertical Motion Along San Andreas Fault System

LOS ANGELES (CBSLA.com) — Is California's most volatile fault line ready to rumble?

A new analysis of GPS data has revealed new areas of motion up and down the roughly 800-mile-long fault that extends as far north as Eureka down to Baja California.

The study published in the journal Nature Geosciences identified 125-mile-wide "lobes" of uplift and subsidence along the San Andreas, which has seen a few millimeters of movement every year along the fault.

Researchers from the University of Hawaii at Mānoa analyzed data collected by the EarthScope Plate Boundary Observatory's GPS array and finally confirmed crustal movement that had long been predicted by computer models.

"While the San Andreas GPS data has been publicly available for more than a decade, the vertical component of the measurements had largely been ignored in tectonic investigations because of difficulties in interpreting the noisy data," said researcher Samuel Howell, lead author of the study. "Using this technique, we were able to break down the noisy signals to isolate a simple vertical motion pattern that curiously straddled the San Andreas fault."

The findings could mean researchers can use GPS vertical motion measurements to better understand - and possibly even predict - behavior of the San Andreas and other fault lines, even when no major ruptures have occurred for decades or centuries.