Remotely Triggered Seismicity in Continental China following the 2008 Mw 7.9 Wenchuan Earthquake

Abstract

We perform a systematic search of remotely triggered seismicity in con- tinental China following the 2008 Mw 7.9 Wenchuan earthquake. We visually identify earthquakes as impulsive seismic energy with clear P and S arrivals on 5 Hz high-pass filtered three-component velocity seismograms 1 hr before and after the Wenchuan earthquake. Out of the 271 stations in the updated Chinese digital seismic network (CSN), 17 stations show statistically significant seismicity increase with β-statistic values larger than 2, following the Wenchuan earthquake. These include 11 stations in the north China block, which is seismically active and is in the rupture propagation direction of the Wenchuan earthquake, three stations along the coastal lines in the relatively stable south China block, one station near the Haiyuan fault zone in north- west China, and two stations near the Tanlu fault zone and the Longgang volcano in northeast China. These observations suggest that dynamic triggering in intraplate regions tends to occur near active faults that have ruptured in historic times and in the rupture propagation directions of the mainshock. However, it is worth noting that many sites that satisfy the criteria are not triggered, suggesting that these conditions would help but are not sufficient enough to guarantee remote triggering in intraplate regions. The tectonic environments near the sites with clear triggered activity range from transpressional to tranextentional, and most regions are not associated with active geothermal or volcanic activity, indicating that dynamic triggering could occur in a wide range of tectonic environments. Online Material: Tables of station information and measured parameters and two supplementary figures showing locally triggered earthquakes.