The San Andreas Fault in California is the most famous crack in the world. Since the great earthquake of 1906 in San Francisco, no one has doubted the fault’s destructive power, released as the pacific crustal plat e slides slowly north past the North American plate. In places the fault lines cross urban and industrial areas where earth quake activity could be potentially devastating.
Our knowledge of why earthquakes happen is a major step towards improved prediction. In 1992 a 7.4 magnitude earthquake in California was mapped by combining satellite radar images take before and after the shock. The closest contours around the fault show the zone of maximum ground displacement. Multiple faulting caused the confuse zone near the epicenter. Radar mapping is more accurate than field surveys, which require monitoring equipment to be set up before shock.