1引言为了能够有效记录学术交流实况,并有助于历次交流内容的查阅和检索,中国地震预报论坛2017-2019年期间的学术交流论文专辑在《国际地震动态》每年第8期出版。2020年度学术交流文集在《地震地磁观测与研究》2021年第2期以“中国地震...1引言为了能够有效记录学术交流实况,并有助于历次交流内容的查阅和检索,中国地震预报论坛2017-2019年期间的学术交流论文专辑在《国际地震动态》每年第8期出版。2020年度学术交流文集在《地震地磁观测与研究》2021年第2期以“中国地震预报论坛学术交流(2020)”专栏形式刊出,中国地震预报论坛2021年度学术交流文集在《地震地磁观测与研究》2021年增刊1刊出。中国地震预报论坛2022年度学术交流文集拟在本《地震地磁观测与研究》2022年增刊1刊出。自2022年开始,在Frontiers in Earth Science出版英文专辑,以扩大宣传中国在地震预报研究领域的最新进展。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
Seismic monitoring using ocean bottom seismometers（OBS） is an efficient method for investigating earthquakes in mid-ocean ridge far away from land. Clock synchronization among the OBSs is difficult without direct co...Seismic monitoring using ocean bottom seismometers（OBS） is an efficient method for investigating earthquakes in mid-ocean ridge far away from land. Clock synchronization among the OBSs is difficult without direct communication because electromagnetic signals cannot propagate efficiently in water. Time correction can be estimated through global positioning system（GPS） synchronization if clock drift is linear before and after the deployment. However, some OBSs in the experiments at the southwest Indian ridge（SWIR） on the Chinese DY125-34 cruise had not been re-synchronized from GPS after recovery. So we attempted to estimate clock drift between each station pairs using time symmetry analysis（TSA） based on ambient noise cross-correlation. We tested the feasibility of the TSA method by analyzing daily noise cross-correlation functions（NCFs） that extract from the data of another OBS experiment on the Chinese DY125-40 cruise with known clock drift and the same deployment site. The results suggest that the NCFs＇ travel time of surface wave between any two stations are symmetrical and have an opposite growing direction with the date. The influence of different band-pass filters,different components and different normalized methods was discussed. The TSA method appeared to be optimal for the hydrophone data within the period band of 2–5 s in dozens of km-scale interstation distances. A significant clock drift of ~2 s was estimated between OBSs sets through linear regression during a 108-d deployment on the Chinese cruise DY125-34. Time correction of the OBS by the ambient noise cross-correlation was demonstrated as a practical approach with the appropriate parameters in case of no GPS re-synchronization.展开更多
文摘1引言为了能够有效记录学术交流实况,并有助于历次交流内容的查阅和检索,中国地震预报论坛2017-2019年期间的学术交流论文专辑在《国际地震动态》每年第8期出版。2020年度学术交流文集在《地震地磁观测与研究》2021年第2期以“中国地震预报论坛学术交流(2020)”专栏形式刊出,中国地震预报论坛2021年度学术交流文集在《地震地磁观测与研究》2021年增刊1刊出。中国地震预报论坛2022年度学术交流文集拟在本《地震地磁观测与研究》2022年增刊1刊出。自2022年开始,在Frontiers in Earth Science出版英文专辑,以扩大宣传中国在地震预报研究领域的最新进展。
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.
基金China Ocean Mineral Resources R&D Association Major Project under contract No.DY135-S1-01the National Natural Science Foundation of China under contract Nos 41506078,41706042 and 41522404the Basic Research Foundation of Second Institute of Oceanography,SOA under contract No.JG0608
文摘Seismic monitoring using ocean bottom seismometers（OBS） is an efficient method for investigating earthquakes in mid-ocean ridge far away from land. Clock synchronization among the OBSs is difficult without direct communication because electromagnetic signals cannot propagate efficiently in water. Time correction can be estimated through global positioning system（GPS） synchronization if clock drift is linear before and after the deployment. However, some OBSs in the experiments at the southwest Indian ridge（SWIR） on the Chinese DY125-34 cruise had not been re-synchronized from GPS after recovery. So we attempted to estimate clock drift between each station pairs using time symmetry analysis（TSA） based on ambient noise cross-correlation. We tested the feasibility of the TSA method by analyzing daily noise cross-correlation functions（NCFs） that extract from the data of another OBS experiment on the Chinese DY125-40 cruise with known clock drift and the same deployment site. The results suggest that the NCFs＇ travel time of surface wave between any two stations are symmetrical and have an opposite growing direction with the date. The influence of different band-pass filters,different components and different normalized methods was discussed. The TSA method appeared to be optimal for the hydrophone data within the period band of 2–5 s in dozens of km-scale interstation distances. A significant clock drift of ~2 s was estimated between OBSs sets through linear regression during a 108-d deployment on the Chinese cruise DY125-34. Time correction of the OBS by the ambient noise cross-correlation was demonstrated as a practical approach with the appropriate parameters in case of no GPS re-synchronization.
