Increasing background seismicity and dynamic triggering behaviors with nearby mining activities around Fangshan Pluton in Beijing, China

Abstract

Abstract Dynamic triggering in western Fangshan Pluton, Beijing, China, has been repeatedly identified, but previous studies are limited by sparse seismic station coverage. Here we systematically analyze continuous waveforms recorded by both permanent stations and a temporary seismic network 40 days before and after the 11 March 2011 M w 9.1 Tohoku‐Oki and the 14 April 2012 M w 8.6 Indian Ocean earthquakes. We first build a template database using a short‐term average to long‐term average method. Next, we apply the matched filter technique that cross correlates the template waveforms with continuous data to detect additional seismic events. Overall, we detect 1956 and 950 seismic events around the Tohoku‐Oki and Indian Ocean main shocks, respectively. Most detected events are shallow (<5 km) and clustered at Beiling Syncline in western Fangshan Pluton, which is adjacent to a running coalmine. Seven and 10 events are detected during the large‐amplitude surface waves of the two main shocks, respectively, but no similar burst is detected following their major foreshock and aftershocks. Multiple statistical tests indicate that the short‐term bursts after the two main shocks are dynamically triggered. We suggest that mining‐related activities may perturb the subsurface stress conditions and hence make the region more susceptible for dynamic triggering than other places.