The researchers found that the San Andreas Fault zone was riddled with fluid-filled fractures, and these fractures sometimes shifted slightly. The repeated earthquakes also became smaller and more frequent, indicating a weakened fault, the researchers said.
On the San Andreas, where things move quickly, you get closed fluid sacs that migrate by 'popping'. For interior earthquakes, you get the fluids migrating through seepage. Either way, the world is starting to come around to my thoughts on the importance of fluid motion. 'No earthquakes without water!" That's my mantra!