Dense array seismology, which is characterized by large number, densely deployed autonomous geophone/seismographs, has received great concerns worldwide recently, especially after the great success of dense array in L...Dense array seismology, which is characterized by large number, densely deployed autonomous geophone/seismographs, has received great concerns worldwide recently, especially after the great success of dense array in Long Beach. One of the biggest curiosity is that if the great success in Long Beach is replicable in China. Hence, we analyze the seismic records from a dense array in Binchuan basin, Yunnan province, which consists of three-component short-period seismographs of three most common domestic models. The Binchuan basin is located near the intersection between the Chenghai-Binchuan fault and the Red River fault,with the latter being the major fault accommodating significant tectonic deformation resulting from eastern extrusion of the Tibetan plateau. Both faults pose serious seismic threats to local residents in Binchuan basin. Basinrange differences, faults, local earthquakes, and a Fixed Airgun Seismic Transmitting Station(FASTS), make the Binchuan basin a perfect experiment site for dense array experiment. The array is named Array of Binchuan(ABC)and the main target is imaging the shallow crustal structure,especially the structure of the basin. To examine the monitoring capability of ABC, we analyze the seismograms to check if they can reveal the basin, the most significant geological feature in the area. Power spectral density analysis,travel time and amplitude analysis of FASTS signals, and amplitude analysis of earthquakes and noise cross-correlation functions are used in the analysis. All the results show correlation with the basin and clear difference between basin and non-basin area. Therefore, the preliminary results support that the ABC has the potential to provide constraints on local structures.展开更多
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supported by the National Natural Science Foundation of China(Grant Nos.41674058,41790463)Chen Yong Academician Workstation in Yunnan province(Grant No.2014IC007)
文摘Dense array seismology, which is characterized by large number, densely deployed autonomous geophone/seismographs, has received great concerns worldwide recently, especially after the great success of dense array in Long Beach. One of the biggest curiosity is that if the great success in Long Beach is replicable in China. Hence, we analyze the seismic records from a dense array in Binchuan basin, Yunnan province, which consists of three-component short-period seismographs of three most common domestic models. The Binchuan basin is located near the intersection between the Chenghai-Binchuan fault and the Red River fault,with the latter being the major fault accommodating significant tectonic deformation resulting from eastern extrusion of the Tibetan plateau. Both faults pose serious seismic threats to local residents in Binchuan basin. Basinrange differences, faults, local earthquakes, and a Fixed Airgun Seismic Transmitting Station(FASTS), make the Binchuan basin a perfect experiment site for dense array experiment. The array is named Array of Binchuan(ABC)and the main target is imaging the shallow crustal structure,especially the structure of the basin. To examine the monitoring capability of ABC, we analyze the seismograms to check if they can reveal the basin, the most significant geological feature in the area. Power spectral density analysis,travel time and amplitude analysis of FASTS signals, and amplitude analysis of earthquakes and noise cross-correlation functions are used in the analysis. All the results show correlation with the basin and clear difference between basin and non-basin area. Therefore, the preliminary results support that the ABC has the potential to provide constraints on local structures.
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.
