The Binchuan region of Yunnan is a structurally complex region with mountains,basins,and active faults.In this situation,seismic wave propagation exhibits complex characteristics due to strong heterogeneity of undergr...The Binchuan region of Yunnan is a structurally complex region with mountains,basins,and active faults.In this situation,seismic wave propagation exhibits complex characteristics due to strong heterogeneity of underground media instead of following the great-circle path.In order to obtain a high-resolution shallow crustal structure,a dense seismic array was deployed during March 21 to May 30,2017 in this area.To better understand the complexities of seismic wave propagation in this region,we perform array-based frequency-domain beamforming analysis and single-station based polarization analysis to investigate the characteristics of seismic wave propagation,using airgun-generated P-wave signals recorded by dense array stations in this experiment.The results from these two methods both reveal similar but complex characteristics of seismic wave propagation in the Binchuan basin.The azimuth anomalies off the great-circle path are quite large with values up to 30°,which is caused by strong structural heterogeneity in the very shallow crust.Our research provide a better understanding of the complex geologic structures in this area and provide guidance for detecting concealed faults and distribution of velocity anomalies.展开更多
基金sponsored by the National Natural Science Foundation of China(GG2080000476)the China Earthquake Science Experiment Project,China Earthquake Administration(2017CESE0101,2018CSES0101)
文摘The Binchuan region of Yunnan is a structurally complex region with mountains,basins,and active faults.In this situation,seismic wave propagation exhibits complex characteristics due to strong heterogeneity of underground media instead of following the great-circle path.In order to obtain a high-resolution shallow crustal structure,a dense seismic array was deployed during March 21 to May 30,2017 in this area.To better understand the complexities of seismic wave propagation in this region,we perform array-based frequency-domain beamforming analysis and single-station based polarization analysis to investigate the characteristics of seismic wave propagation,using airgun-generated P-wave signals recorded by dense array stations in this experiment.The results from these two methods both reveal similar but complex characteristics of seismic wave propagation in the Binchuan basin.The azimuth anomalies off the great-circle path are quite large with values up to 30°,which is caused by strong structural heterogeneity in the very shallow crust.Our research provide a better understanding of the complex geologic structures in this area and provide guidance for detecting concealed faults and distribution of velocity anomalies.
