Fig. 12

Hypocentral distances from the first earthquake with colors of stress drops as a function of an elapsed time of less than (a) 1 h and b 50 h. White circles indicate earthquakes without estimates of their stress drops. c Hypocentral distances with scales of source radii as a function of an elapsed time of less than 1 h. d The same as (c) for an elapsed time of less than 50 h. Vertical orange bars indicate the source dimensions calculated from values of the stress drop that were estimated by the S wave spectral ratios (Table 1)