Fig. 3

Spatiotemporal evolution of seismicity revealed via the matched filter technique. a Space–time diagram of the detected events, which are shown as circles that are scaled to earthquake magnitude and colored to hypocentral depth. The blue and red stars denote the foreshock and mainshock events, respectively. DTZ indicates the zone with delayed triggered aftershocks. b Time series of the ratio of the cumulative number of background events to the total events in the two following areas. Blue curve: 2.3 km < Y < 6.3 km (DTZ). Black curve: − 4 km < Y < 2.3 km. Note that the mainshock event is located at Y = 0 km. Background events are earthquakes that were not triggered by other earthquakes. See the “Methods” section for further details