Coulomb stress changes and seismicity in central Taiwan due to the Nantou blind-thrust earthquakes in 2013

Abstract

Due to the two earthquakes, 27 March 2013 event (ML6.2, namely 0327 event) and 2 June 2013 event (ML6.5, namely 0602 event), occurring at the Nantou area of the central Taiwan, we investigate the relationship between the Coulomb stress changes and the seismicity in the paper. We first employed the refined homomorphic deconvolution method to invert the kinematic source processes of these two earthquakes from the teleseismic data recorded by Incorporated Research Institutions for Seismology (IRIS), and then calculated the Coulomb stress changes of these two events. The total durations of the rupture process for the 0327 and 0602 events were 12s and 15s, respectively. The epicenter of the 0602 event and the epicenters of the aftershocks (ML>3) of the 0327 event were concentrated in a region with positive Coulomb stresses caused by the 0327 event. This indicates that the derived source process was available and coincided with physical properties in a manner that strongly suggests that the 0602 event was triggered by the 0327 event. According to the Coulomb stress changes caused by the 0602 event at a depth of 4km and its vertical cross section, most of the aftershocks (ML>3) of the 0602 event were located in a region with positive Coulomb stress changes greater than 0.1bar. In addition, almost all the epicenters of the earthquakes (ML>3) in central Taiwan between July 15, 2013, and January 27, 2015, were located in a region with positive Coulomb stress changes at a depth of 6km contributed by the 0327 and 0602 events. These findings indicate that if the background stress in the central Taiwan is intense high, the Coulomb stress changes contributed by the two events may affect the seismicity of central Taiwan in this period of time, and that a region with extreme positive Coulomb stress changes may be the place in which potential earthquakes will occur in the future. Moreover, the proposed inversion method can derive the proper source model efficiently without any statistical assumptions.