Fig. 4

Schematic relation between aftershocks and co-seismic rupture. The mainshock started with a thrust mechanism and transitioned into a strike-slip mechanism before rupture arrest with total rupture length of about 300 km. Surface rupture is not observed for the north-easternmost 50 km, and the early aftershocks occurred at depths up to 18 km while later aftershocks (late July and early August) became shallower, as little as 2 km. These shallow earthquakes may be the result of filling the unruptured portion of the co-seismically ruptured fault. However, most other aftershocks in the northern segment and middle segment show thrust mechanisms, contrasting with the gradually increasing strike-slip component of surface rupture observed in the field.