The San Andreas Fault is part of a giant "Z" of faults; the top of the "Z" consists of the Ridgecrest Fault, the middle is the Garlock Fault and the bottom is the southern part of the famous San Andreas. If the "top-of-the-Z" Ridgecrest Fault were to have a really big earthquake (at least a magnitude 7.5), that could trigger an earthquake on the "middle-of-the-Z" Garlock Fault, which, in turn, could cause a massive earthquake along the "bottom-of-the-Z" San Andreas, a new study finds. These successive earthquakes wouldn't necessarily happen all at once, but over a period of time (perhaps...