摘要
2019年9月8日四川威远M_(S)5.4地震和12月18日资中M_(S)5.2地震位于“长宁-威远国家级页岩气产业示范区”,地震发生后备受工业界、地震学界和政府的高度关注.将深度学习方法与传统定位方法相结合,快速构建高精度地震目录,对充分高效利用地震波形资料,提升地震检测能力,分析地震序列的时空演化特征、讨论发震构造模型和发震机制具有十分重要意义.本文利用最新发展和应用较广的震相自动拾取技术(PhaseNet)、快速震相自动关联技术(REAL),对荣县—威远—资中附近22个临时地震监测台站四个多月连续记录的波形进行初至P和S波震相拾取、震相自动关联和初步定位,并先后应用传统绝对定位和相对定位技术,获得了荣县—威远—资中地区高精度地震目录,据此利用断层三维建模技术构建了威远M_(S)5.4和资中M_(S)5.2两次地震的发震断层三维几何结构模型,揭示出威远M_(S)5.4和资中M_(S)5.2两地震序列具有相类似的空间分布特征,且空间分布形态与震源机制解一致,结合断层三维几何结构模型,推测两次地震发震构造为同一条先存隐伏逆冲断层,且与流体孔隙压力扩散致使断层活化有关,威远M_(S)5.4地震的发生对资中M_(S)5.2地震具有一定的触发作用.此外,荣县地区的地震活动分布也同样揭示了逆冲断层活动性质,密集小震级事件活动也与水力压裂具有一定关系.
Occurrence of the Sept.8,2019 Weiyuan M_(S)5.4 and Dec.18,2019 Zizhong M_(S)5.2 earthquakes one after another,which are located in the Changning-Weiyuan National Shale Gas Demonstration Zone,has attracted more attentions from the industry,seismological community and government.Combining the deep learning phase-picking method with the traditional earthquake relocation method to rapidly construct a highprecision earthquake catalog is crucial for the effective utilization of seismic waveform data,improving microseismic detection capabilities,analyzing spatiotemporal seismic evolution characteristics,and investigating seismogenic structural models and earthquake mechanisms of earthquake sequences.In this study,we use the latest developed and widely-used seismic phase automatic picking method(PhaseNet)and phase association method(REAL)to analyze the more than four-month-long continuous waveform recordings from the 22 temporary seismic stations in the Rongxian-Weiyuan-Zizhong area.We first pick seismic P and S first arrival phases using PhaseNet and the REAL to associate with a particular earthquake,with preliminary locations determined by grid search.The Hypo-Inverse absolute relocation and HypoDD methods are successively used to obtain the high precision relocated earthquake catalog in the Rongxian-Weiyuan-Zizhong area.Based on the relocated earthquake catalog,3D fault modeling techniques are employed to construct seismogenic fault models for the Weiyuan M_(S)5.4 and Zizhong M_(S)5.2 earthquakes.The relocated earthquake catalog reveals the spatiotemporal distribution characteristics of the Weiyuan M_(S)5.4 and Zizhong M_(S)5.2 earthquake sequences,supported also by the corresponding earthquake focal solutions.Integrating with the 3D geometric structural model of the fault,it can be inferred that the seismogenic structures responsible for both earthquakes are linked to a common,pre-existing thrust fault,whose activation is plausibly associated with the diffusion of fluid pore pressure.Notably,the occurrence of the Weiyuan M_(S)5.4 earthquake appears to play a pivotal role in triggering the Zizhong M_(S)5.2 earthquake.In addition,the seismic distribution within the Rongxian area also reveals the activity of thrust fault.The intensive occurrence of small-magnitude earthquakes demonstrates an apparent correlation with hydraulic fracturing activities.
作者
罗佳宏
徐锡伟
李海鸥
王启欣
鲁人齐
陈桂华
马文涛
LUO JiaHong;XU XiWei;LI HaiOu;WANG QiXin;LU RenQi;CHEN GuiHua;MA WenTao(State Key Laboratory of Earthquake Dynamics and Forecasting,Institute of Geology,China Earthquake Administration,Beijing 100029,China;School of Earth Sciences and Resources,China University of Geosciences,Beijing,100083,China;National Institute of Natural Hazards,Ministry of Emergency Management of China,Beijing 100085,China)
出处
《地球物理学报》
北大核心
2025年第9期3446-3463,共18页
Chinese Journal of Geophysics
基金
国家自然科学基金重大项目(41941016)
中国地震局地质研究所基本科研业务专项(IGCEA2406)共同资助.
