Space-time heterogeneity in aftershock activity

For a number of aftershock sequences in and around Japan, we examine detrended space—time coordinates after fitting the Omori–Utsu occurrence rate to each aftershock sequence. The case studies in conjunction with the fault locations and orientations of the main shocks and focal large aftershocks indicate that the region of deficit and surplus in the aftershock activity well corresponds to the decreased and increased region of Coulomb failure stress, respectively, caused by various aseismic slips. We illustrate the relation between the transient stress changes and the anomalous aftershock activity in a local subregion by six scenarios derived from the rate and state dependent friction law of Dietrich.