The map shows all recorded seismic events that have occurred in southern California in the years from 1932 through 1996, each quake represented by a single red pixel (many overlap). Plotted for reference on the background are the surface traces of the major faults in the area (shown as light blue-green lines -- the most prominent being the San Andreas fault, which runs from the lower right corner to the upper left corner of the map) and the major area highways (shown in yellow).