Seismic relocation, focal mechanism and crustal seismic anisotropy associated with the 2010 Yushu MS7.1 earthquake and its aftershocks
Bo Zhao1, 2, Yutao Shi2, 3, Yuan Gao2
1 China Earthquake Networks Center, Beijing 100045, China 2 Institute of Earthquake Science, China Earthquake Administration, Beijing 100036, China 3 Institute of Geophysics, China Earthquake Administration, Beijing 100081, China
Seismic relocation, focal mechanism and crustal seismic anisotropy associated with the 2010 Yushu MS7.1 earthquake and its aftershocks
Bo Zhao1, 2, Yutao Shi2, 3, Yuan Gao2
1 China Earthquake Networks Center, Beijing 100045, China 2 Institute of Earthquake Science, China Earthquake Administration, Beijing 100036, China 3 Institute of Geophysics, China Earthquake Administration, Beijing 100081, China
摘要The 2010 Yushu MS7.1 earthquake occurred in Ganzi-Yushu fault, which is the south boundary of Bayan Har block. In this study, by using double difference algorithm, the locations of mainshock (33.13°N, 96.59°E, focal depth 10.22 km) and more than 600 aftershocks were obtained. The focal mechanisms of the mainshock and some aftershocks with MS>3.5 were estimated by jointly using broadband velocity waveforms from Global Seismic Network (GSN) and Qinghai Seismic Network as well. The focal mechanisms and relocation show that the strike of the fault plane is about 125 ? (WNW–ESE), and the mainshock is left-laterally strikeslip. The parameters of shear-wave splitting were obtained at seismic stations of YUS and L6304 by systematic analysis method of shear-wave splitting (SAM) method. Based on the parameters of shear-wave splitting and focal mechanism, the characteristics of stress field in seismic source zone were analyzed. The directions of polarization at stations YUS and L6304 are different. It is concluded that after the mainshock and the MS6.3 aftershock on April 14, the stress-field was changed.
Abstract：The 2010 Yushu MS7.1 earthquake occurred in Ganzi-Yushu fault, which is the south boundary of Bayan Har block. In this study, by using double difference algorithm, the locations of mainshock (33.13°N, 96.59°E, focal depth 10.22 km) and more than 600 aftershocks were obtained. The focal mechanisms of the mainshock and some aftershocks with MS>3.5 were estimated by jointly using broadband velocity waveforms from Global Seismic Network (GSN) and Qinghai Seismic Network as well. The focal mechanisms and relocation show that the strike of the fault plane is about 125 ? (WNW–ESE), and the mainshock is left-laterally strikeslip. The parameters of shear-wave splitting were obtained at seismic stations of YUS and L6304 by systematic analysis method of shear-wave splitting (SAM) method. Based on the parameters of shear-wave splitting and focal mechanism, the characteristics of stress field in seismic source zone were analyzed. The directions of polarization at stations YUS and L6304 are different. It is concluded that after the mainshock and the MS6.3 aftershock on April 14, the stress-field was changed.
基金资助:basic research project of Institute of Earthquake Science of China Earthquake Science (No. 2009-21) and National Natural Science Foundation of China (No. 41040034)
通讯作者:
Bo Zhao
E-mail: zhaobo@seis.ac.cn
引用本文:
Bo Zhao, Yutao Shi, Yuan Gao. Seismic relocation, focal mechanism and crustal seismic anisotropy associated with the 2010 Yushu MS7.1 earthquake and its aftershocks[J]. 《地震学报》英文版, 2012, 25(1): 111-119.
Bo Zhao, Yutao Shi, Yuan Gao. Seismic relocation, focal mechanism and crustal seismic anisotropy associated with the 2010 Yushu MS7.1 earthquake and its aftershocks. Earthquake Science, 2012, 25(1): 111-119.
