为检验震源机制解谱聚类方法的实用性,选择新丰江库区为研究区域,利用FOCMEC方法反演了该区域2012年1月1日—2018年12月31日M_L2.0以上地震的震源机制解,并对其进行了谱聚类分析,最终获得该区域7种震源机制解类型; 通过分析每种类型的震源机制解特征及其时空分布特征,探讨了震源机制解类型分布与区域构造的关系。结果表明:①新丰江库区地震破裂类型以正断型为主,兼有部分倾滑分量,其次为走滑型; ②不同类型的震源机制解具有区域性的空间分布特征,主要受不同的构造背景影响,反映了新丰江库区地震活动和构造特征之间的关系; ③不同类型震源机制解所描述的断裂分布反映了峡谷及大坝区库水渗透的构造条件,解释了区域地震频发的可能原因; ④每种类型的震源机制解在研究时间范围内数量变化较为稳定。

In order to test the practicability of spectral clustering for focal mechanism solutions,we took Xinfengjiang reservoir as the case study area and applied a mechanism inversion to seismic events(M_L≥2.0,2012-2018),by using P wave polarity and amplitude ratio of P and S wave. Then,spectral cluster analysis was applied to these focal mechanism solutions which were clustered 7 types finally. By analyzing the temporal and spatial characteristics of each cluster,we investigated the relationship between clusters and regional structures and reached following conclusions:① The earthquake rupture type in Xinfengjiang reservoir is majorly normal-faulting type with partial dip-slip components,and is slightly strike-slip type. ② Mechanism variations were strongly associated with corresponding hypocentral structure,which reflected the relationship between seismic activity and structures in Xinfengjiang reservoir. ③ The faults described by clusters reflected the structural conditions of reservoir water infiltration,that explained the possibility of frequent regional earthquakes,in Canyon and dam area. ④The clusters changed relatively steadily within the research time frame.

P315

地震监测、预测、科研三结合课题(3JH-202301026)、震情跟踪定向工作任务(2023010108)、广东省地震局青年地震科学基金(重点实验室开放项目GDDZZ202306)共同资助