Figure 7. Spatiotemporal evolution of the hypocenters (a )–(c ) before and (d)–(f ) after the mainshock. (a ) Projection of the hypocenters, (d ) map view, (b ) and (e ) east–west cross section, and (c ) and (f ) north–south cross section. The symbol sizes corresponds to the JMA magnitude. The hypocenters are colored according to their occurrence time measured relative to that of the mainshock, that is, the mainshock occurred at time 0 and negative and positive numbers denote the days before and after the mainshock, respectively.