Spatiotemporal seismicity pattern of the Taiwan orogen

Abstract. We investigate the temporal and spatial seismicity patterns prior to eight M > 6 events nucleating in different regions of Taiwan through a region–time–length algorithm and an analysis of a self-organizing spinodal model. Our results show that the spatiotemporal seismicity variations during the preparation process of impending earthquakes display distinctive patterns corresponding to tectonic settings. Q-type events occur in southern Taiwan and experience a seismic quiescence stage prior to the mainshock. A seismicity decrease of 2.5 < M < 4.5 events occurs around the relatively high b-value southern Central Range, which contributes to the accumulation of tectonic stress for preparing for the occurrence of the Q-type event. On the other hand, A-type events occur in central Taiwan and experience a seismic activation stage prior to the mainshock, which nucleates on the edge of the seismic activation area. We should pay attention when accelerating seismicity of 3 < M < 5 events appears within the low b-value area, which could promote the nucleation process of the A-type event.