摘要
芦山地区在2013年和2022年发生两次6.0级以上地震,本研究收集两次地震的余震序列,研究两次芦山地震发震断层的几何参数和滑动特性,并分析汶川地震和2013年芦山地震对2022年芦山地震的应力影响.得到以下结论:(1)基于收集到的两次芦山地震序列的2531个地震事件的精确定位结果,采用模糊聚类方法,求解得到芦山地震序列的5个发震断层面位置及其走向和倾角,5个断层面在空间上呈花状构造分布.(2)基于收集和计算得到的该地区的127个震源机制中心解,求解得到该地区的构造应力场,得到芦山地区形成了SEE—NWW向挤压,垂直向拉张的以逆冲为主的应力状态.(3)通过将构造应力场投影到两次芦山地震发震断层上,得到这些发震断层面上均容易发生逆冲型破裂事件.(4)将求解的2022年芦山地震序列发震断层面形状和滑动特性作为接收断层参数,计算汶川地震和2013年芦山地震对2022年芦山地震序列的应力影响,结果显示汶川地震对2022年芦山地震序列发震断层面的活动性起到促进作用,而汶川地震和2013年芦山地震的共同作用,对2022年芦山地震序列发震断层面的活动性起到抑制作用,即2013年芦山地震的发生推迟了2022年芦山地震序列的发生.基于GPS观测的应变率得到,在汶川地震和2013年芦山地震的共同作用下,2022年芦山地震被推迟的时间约为5.2~10.5年.这些研究对研究龙门山推覆构造带南段的断层活动特性和地震危险性评估有一定意义.
There were two earthquakes of magnitude 6.0 or higher that occurred in Lushan region in 2013 and 2022.The present study the geometrical parameters and slip characteristics of the seismogenic faults associated with both of the two Lushan earthquakes,based on the collected aftershock sequences,Additionally,the stress influence of the Wenchuan earthquake and the 2013 Lushan earthquake on the 2022 Lushan earthquake was analyzed.The following conclusions are obtained:(1)The fuzzy clustering method was used to estimate the location,strike and dip angle of the 5 seismogenic fault planes in Lushan region,based on 2531 seismic events that were accurately located from the two earthquake sequences.A spatial analysis revealed that these 5 faults are distributed in a floral structure pattern.(2)After collating and calculating the 127 central focal mechanisms from this area,the tectonic stress field was determined to be a thrust type stress state with compression occurring in SEE—NWW direction and extension of nearly vertical direction.(3)By projecting the tectonic stress field onto the two seismogenic faults of the Lushan earthquakes,it was found that both of these faults are prone to reverse-faulting events.(4)The receiving fault parameters utilized for the 2022 Lushan earthquake sequence were based on the geometric parameters of its fault plane.By estimation,the stress influence of the Wenchuan earthquake and the 2013 Lushan earthquake on the 2022 Lushan earthquake were estimated.The results show that the Wenchuan earthquake promoted the activity of the seismogenic faults that triggered the Lushan earthquake sequence in 2022,while under the combined influence of the Wenchuan earthquake and the 2013 Lushan earthquake,the activity of the seismogenic faults that caused the Lushan earthquake sequence in 2022 was suppressed.Based on GPS observations of the strain rate,it was found that the combined effects of the Wenchuan earthquake and the 2013 Lushan earthquake caused a delay time of approximately 5.2~10.5 years for the occu
作者
靳志同
万永革
王福昌
李枭
冯淦
许英才
JIN ZhiTong;WAN YongGe;WANG FuChang;LI Xiao;FENG Gan;XU YingCai(Institute of Disaster Prevention,Sanhe Hebei 065201,China;Hebei Key Laboratory of Earthquake Dynamics,Sanhe Hebei 065201,China;Earthquake Agency of Ningxia Hui Autonomous Region,Yinchuan 750001,China)
出处
《地球物理学报》
SCIE
EI
CAS
CSCD
北大核心
2024年第6期2202-2219,共18页
Chinese Journal of Geophysics
基金
河北省教育厅科学技术研究项目(ZD2022160)
国家自然科学基金(42174074,41674055)
中央高校科研业务费专项(ZY20215117)
河北省地震动力学重点实验室开放基金项目(FZ212105)共同资助。
关键词
芦山地震序列
模糊聚类
断层面估计
断层面滑动特性
地震应力影响
Lushan earthquake sequence
Fuzzy clustering
Fault plane estimation
Slip characteristics of the fault
Seismic stress influence
