5an-andreas-faultA small part of the San Andreas Fault that was thought to quietly slide without shaking its neighbors may actually be capable of strong earthquakes, including magnitude-6 shakers, a new study finds. The San Andreas Fault is divided into three legs. The middle leg has long been treated as a benign barrier between the more seismically active northern and southern segments. That’s because the central section “creeps” — rocks on either side of the fault slip past each other without snagging. On the other two legs, rocks lock together, building up strain that is unleashed as powerful earthquakes. In the new study, researchers created a 3D computer model showing where the San Andreas Fault slips and where it is locked. The model is based on GPS measurements and satellite monitoring of surface deformations, such as tiny changes in elevation. The findings were published online Dec. 20, 2014, in the journal Geophysical Research Letters. More