The Binchuan region is located in a seismically active area in northwestern Yunnan,China.The detailed crustal structure is important to understand the tectonic evolution and to assess the seismic hazard in the study a...The Binchuan region is located in a seismically active area in northwestern Yunnan,China.The detailed crustal structure is important to understand the tectonic evolution and to assess the seismic hazard in the study area.With a 2-D dense array deployed in this region,we use teleseismic receiver function traditional imaging methods,including the H-κand common-conversion-point stacking methods,to derive high-resolution crustal thickness and vP/vS ratio maps.Our results indicate that the crustal thickness increases from~40 km to~46 km in the south-north direction,and the average crustal thickness beneath the Binchuan basin is~42 km.Our results agree with previous results but have higher resolution due to dense interstation spacing.展开更多
We estimated Moho depth beneath the southern Tanlu fault zone and its adjacent area using common-conversion-point(CCP)stacking of receiver functions,which were computed from teleseismic records of the CEArray.Our esti...We estimated Moho depth beneath the southern Tanlu fault zone and its adjacent area using common-conversion-point(CCP)stacking of receiver functions,which were computed from teleseismic records of the CEArray.Our estimated Moho depth matches well with 2-D profiles derived from active-source deep seismic reflection surveys,suggesting that the calculated the Moho depth map is likely accurate beyond the 2-D profiles.Overall,the estimated Moho depth map showed a high spatial correlation with tectonic provinces,i.e.,Moho topographic boundaries are in good agreement with geological boundaries.Beneath the Dabie orogenic belt and the mountainous areas in southern Anhui Province,the Moho lies relatively deep,and there is an obvious difference in Moho depth between the two sides of this segment of the Tanlu fault.We further selected four depth profiles with dense instrumentation to show Moho depth changes across different tectonic blocks in the study area.We saw two step-like changes in Moho depth beneath the Xiangfan-Guangji and Gushi-Feizhong,which run parallel along the WNW-ESE direction and delineate the southern and northern bounds of the northern Dabie orogenic belt,which is likely the suture zone between the North China Block and South China Block.Crust beneath the northeast corner of the study area is significantly thinner than other areas,which is consistent with the crustal detachment model proposed for suturing between the North and South China blocks in the region east to the Tanlu fault.展开更多
We resolve a large （-20 km） discrepancy in Moho depth determined from PdS receiver functions （RFs） and from active source seismic profiling in the complex Caribbean-South American plate boundary zone in eastern Ve...We resolve a large （-20 km） discrepancy in Moho depth determined from PdS receiver functions （RFs） and from active source seismic profiling in the complex Caribbean-South American plate boundary zone in eastern Venezuela. As part of the BOLIVAR experiment 20 broadband stations were deployed along an active source profile to record teleseisms. Using the extremely heterogeneous crustal model obtained from active source data, we generated 2D finite-difference elastic wave synthetics and from them calculated receiver functions and CCP stacks. We compare the observations with synthetic sections that have been spatially sampled at 0.25 km to 40 km. The densely sampled synthetics show that several events in the field data that were originally interpreted as the Moho are multiple reflections within sedimentary basins. Where the Moho has the steepest dip under the plate boundary the CCP stacks fail to image the Moho well, regardless of the density of spatial sampling. A suitable spatial sampling criterion for clearly imaging the lower crust and Moho is to overlap Fresnel zones by 50% at Moho depth, which for the 1 Hz receiver functions examined here, requires an instrument spacing of 15-20 km, with the actual field data density ranging from 20 km to 100 km.展开更多
基金supported by the National Key R&D Program of China(No.2018YFC1503400)China Earthquake Science Experiment Project,CEA(Nos.2018CSES0101,2018CSES0102 and 2019CSES0107)+2 种基金HKSAR Research Grant Council GRF(No.14305617)CUHK Direct Grant from Faculty of Science,National Natural Scientific Foundation of China(Nos.41974069 and 41790463)Chen Yong Academician Workstation of Yunnan Province in China(No.2014IC007)。
文摘The Binchuan region is located in a seismically active area in northwestern Yunnan,China.The detailed crustal structure is important to understand the tectonic evolution and to assess the seismic hazard in the study area.With a 2-D dense array deployed in this region,we use teleseismic receiver function traditional imaging methods,including the H-κand common-conversion-point stacking methods,to derive high-resolution crustal thickness and vP/vS ratio maps.Our results indicate that the crustal thickness increases from~40 km to~46 km in the south-north direction,and the average crustal thickness beneath the Binchuan basin is~42 km.Our results agree with previous results but have higher resolution due to dense interstation spacing.
基金This research is supported by Spark Program of Earthquake Sciences(No.XH20026)Joint Open Fund of Mengcheng National Geophysical Observatory(No.MENGO-202014).
文摘We estimated Moho depth beneath the southern Tanlu fault zone and its adjacent area using common-conversion-point(CCP)stacking of receiver functions,which were computed from teleseismic records of the CEArray.Our estimated Moho depth matches well with 2-D profiles derived from active-source deep seismic reflection surveys,suggesting that the calculated the Moho depth map is likely accurate beyond the 2-D profiles.Overall,the estimated Moho depth map showed a high spatial correlation with tectonic provinces,i.e.,Moho topographic boundaries are in good agreement with geological boundaries.Beneath the Dabie orogenic belt and the mountainous areas in southern Anhui Province,the Moho lies relatively deep,and there is an obvious difference in Moho depth between the two sides of this segment of the Tanlu fault.We further selected four depth profiles with dense instrumentation to show Moho depth changes across different tectonic blocks in the study area.We saw two step-like changes in Moho depth beneath the Xiangfan-Guangji and Gushi-Feizhong,which run parallel along the WNW-ESE direction and delineate the southern and northern bounds of the northern Dabie orogenic belt,which is likely the suture zone between the North China Block and South China Block.Crust beneath the northeast corner of the study area is significantly thinner than other areas,which is consistent with the crustal detachment model proposed for suturing between the North and South China blocks in the region east to the Tanlu fault.
文摘We resolve a large （-20 km） discrepancy in Moho depth determined from PdS receiver functions （RFs） and from active source seismic profiling in the complex Caribbean-South American plate boundary zone in eastern Venezuela. As part of the BOLIVAR experiment 20 broadband stations were deployed along an active source profile to record teleseisms. Using the extremely heterogeneous crustal model obtained from active source data, we generated 2D finite-difference elastic wave synthetics and from them calculated receiver functions and CCP stacks. We compare the observations with synthetic sections that have been spatially sampled at 0.25 km to 40 km. The densely sampled synthetics show that several events in the field data that were originally interpreted as the Moho are multiple reflections within sedimentary basins. Where the Moho has the steepest dip under the plate boundary the CCP stacks fail to image the Moho well, regardless of the density of spatial sampling. A suitable spatial sampling criterion for clearly imaging the lower crust and Moho is to overlap Fresnel zones by 50% at Moho depth, which for the 1 Hz receiver functions examined here, requires an instrument spacing of 15-20 km, with the actual field data density ranging from 20 km to 100 km.
