Dynamically triggered aftershock activity and far-field microearthquakes following the 2014 M(s)7. 3 Yutian, Xinjiang Earthquake

Abstract

We systematically examine how dynamic stresses from seismic waves following the 2014 M(s)7. 3 Yutian, Xinjiang, earthquake affect aftershocks and regional microseismicity in the near and far field. The full Coulomb stress changes are computed based on the discrete wavenumber method. We find that the static Coulomb stress changes caused by the M(s)7. 3 earthquake discourage aftershocks occurrence in the southwestern part of the aftershock zone, which may explain why the aftershock activity in this region is relatively weak. Aftershock rates at the region about 30 km to the northeast of the mainshock are relatively high, which are consistent with positive dynamic and static stress changes in that region, with the peak values of 2. 78 MPa and 0. 80 MPa, respectively. Aftershocks about 45 km north of the mainshock are mostly triggered by the dynamic stress change with a peak value of 0. 72 MPa. The peak values of dynamic stress change in the remote Shaya and Jiashi areas are 0. 09 MPa and 0. 1 MPa, respectively, which are high enough to trigger microearthquakes in these areas. Overall the spatial distributions of dynamic stress changes induced by the Yutian mainshock show asymmetrical patterns, and there is a positive correlation between the aftershock distribution and the positive area of dynamic stress change in the northeastern and northern regions.