Near-field triggering of microearthquakes along the Longitudinal Valley fault in eastern Taiwan

Dynamic earthquake triggering as a well-documented phenomenon can provide valuable information for studying the stress loading cycle from failure on faults. In this study, seismicity rate changes were investigated in the Longitudinal Valley fault (LVF) following the 2019 M_L5.2 Hualien earthquake, which occurred offshore in eastern Taiwan. After the matched filter technique was applied to continuous waveform data, twice as many microearthquakes were newly detected in the vicinity of the LVF compared with the number listed in the Taiwan Weather Bureau catalog. Seismicity rates in the northern segment of the LVF increased immediately following the Hualien mainshock, which indicated dynamic triggering during the passage of seismic waves. Statistical analysis suggested that following seismic events might be attributed to fault slipping or creeping. These findings show that the observation of earthquake triggering can provide valuable assistance in monitoring the stress perturbations of active faults.