Tiny Clays Tame Earthquake Faults View looking southeast along
the surface trace of the San Andreas fault in the Carrizo Plain,
north of Wallace Creek. Elkhorn Rd. meets the fault near the top
of the photo. CREDIT: Scott Haefner, USGS California's San
Andreas Fault is associated with some of the most destructive
earthquakes in U.S. history, but some parts of the fault system
are much quieter than others, rubbing smoothly against each
other rather than sticking and then jerking loose in a huge
rupture. A new study of samples from these more leisurely fault
sections has revealed that tiny particles of clay keep these
sections lubricated and less likely to violently shake. The
relatively smooth movement that occurs in some sections of
faults is called creep. The question of why some fault zones
creep slowly and steadily while others lock for a time and then
shift suddenly and violently, spawning earthquakes, has long
puzzled scientists. What's going on Some have speculated that
fluids facilitate slippage, while