Figure 9. Spatial distribution of stress drop in the 3 time periods (a-c) with only Mw>1.1 earthquakes, coded by the log10 stress drop values in every 4km-by-2km block for grids at increment of 0.5km both horizontally and vertically. The yellow star is the location of SAFOD, and yellow circles are the locations of the 1996 M6 and 2004 M6 earthquakes. The gray open circles are the seismicity included in this study. Dashed curves outline four regions for detailed discussion: I. SAFOD area, II. Creeping Zone, III. 1966 M6 area, IV. Locked zone.