摘要Using seismic data of the aftershocks sequence of the April 20, 2013 Lushan earthquake recorded by seismic temporary and permanent stations in the source region, with the visual inspection of particle motion diagrams, this paper preliminarily contains the polarization directions of fast shear wave and the time-delays of split shear waves at every station, and analyzes the crustal anisotropic characteristics in the source region. In the study area, the polarization directions at stations BAX, TQU, L132, L133, L134, and L135 are northeast, which is consistent with the strike of Dachuan– Shuangshi fault. There are two polarization directions at MDS and L131, which are northeast and southeast. The scatter of polarization directions suggests the complex stress field around these two stations where two faults intersect. For the normalized time-delays at every station, the range is 1.02–8.64 ms/km. The largest time-delay is from L134 which is closest to the mainshock, and the smallest one is from L133. The variations in time-delays show the decreasing at stations BAX, L134, and L135 because of the stress–relaxation after earthquake.
Abstract：Using seismic data of the aftershocks sequence of the April 20, 2013 Lushan earthquake recorded by seismic temporary and permanent stations in the source region, with the visual inspection of particle motion diagrams, this paper preliminarily contains the polarization directions of fast shear wave and the time-delays of split shear waves at every station, and analyzes the crustal anisotropic characteristics in the source region. In the study area, the polarization directions at stations BAX, TQU, L132, L133, L134, and L135 are northeast, which is consistent with the strike of Dachuan– Shuangshi fault. There are two polarization directions at MDS and L131, which are northeast and southeast. The scatter of polarization directions suggests the complex stress field around these two stations where two faults intersect. For the normalized time-delays at every station, the range is 1.02–8.64 ms/km. The largest time-delay is from L134 which is closest to the mainshock, and the smallest one is from L133. The variations in time-delays show the decreasing at stations BAX, L134, and L135 because of the stress–relaxation after earthquake.
基金资助:Research Project in Earthquake Science (Nos. 201308018 and No. 201108002), Seismic Industry- Specific Program (200708009) and National Natural Science Foundation of China (No. 40904012)
通讯作者:
Sha Liu
E-mail: liusha@cea-igp.ac.cn
引用本文:
Sha Liu, Jiansi Yang, Baofeng Tian, Yu Zheng, Xudong Jiang, Zhiqiang Xu. The characteristics of shear wave splitting in the source region of the April 20, 2013 Lushan earthquake[J]. 《地震学报》英文版, 2013, 26(3-4): 223-228.
Sha Liu, Jiansi Yang, Baofeng Tian, Yu Zheng, Xudong Jiang, Zhiqiang Xu. The characteristics of shear wave splitting in the source region of the April 20, 2013 Lushan earthquake. Earthquake Science, 2013, 26(3-4): 223-228.
