重庆地区地震震源机制解及动力环境分析  

Focal Mechanisms of Earthquakes in Chongqing and Geodynamical Implications

作　　者：冯梅[1] 安美建[1] 吴中海[2] 谭成轩[2] FENG Mei;AN Mei-jian;WU Zhong-hai;TAN Cheng-xuan(Chinese Academy of Geological Sciences,Beijing 100037;Institute of Geomechanics,Chinese Academy of Geological Sciences,Beijing 100081)

机构地区：[1]中国地质科学院,北京100037 [2]中国地质科学院地质力学研究所,北京100081

出　　处：《地球学报》2019年第2期319-328,共10页Acta Geoscientica Sinica

基　　金：中国地质调查局地质调查项目(编号:DD20160268);国家自然科学基金面上项目(编号:41574049)联合资助~~

摘　　要：使用中国地震台网约100台原始观测波形数据,利用FOCMEC震相法确定了2017年11月23日5.0级重庆武隆和2016年12月27日4.9级重庆荣昌地震的震源机制解。同时搜集了重庆地区近年来其它震源机制资料。结果显示武隆地震属于走滑正断型,与2013年发生在七曜山断裂带中段的石柱地震活动性质相似,推断七曜山断裂以正断活动为主。发生在华蓥山断裂带南段的荣昌地震属于走滑逆冲型,推断华蓥山断裂(南段)以逆冲活动为主。从区域震源机制解结果看,华蓥山断裂南段所在的重庆西部主要受近东西向挤压构造应力控制,与华南区域构造应力场一致。七曜山断裂带所在的重庆中东部主要受近南北向挤压应力控制,与现今华南区域构造应力场不一致。推断重庆中东部处于一个与周围应力和构造活动方式不同的独特环境。综合新生代构造资料推断,青藏高原隆升基本没有影响华蓥山断裂带以东地区。重庆中东部至两湖平原地区处于特提斯构造域和环太平洋构造域的转换过渡区,其独特的应力环境表明该区现今似乎不受两大构造域的影响。Using waveforms recorded by about one hundred seismic stations of the China Seismic Network and the phase-based method of FOCMEC,the authors determined focal mechanisms of the Ms 5.0 earthquake that occurred on November 23,2017,in Wulong and the Ms 4.9 earthquake on December 27,2016,in Rongchang.The authors also collected focal mechanisms of other earthquakes which recently occurred in Chongqing.The results show that the Wulong earthquake along southern Qiyaoshan fault was an oblique normal fault activity,similar to another earthquake recently occurred in Shizhu along central Qiyaoshan fault.It is therefore inferred that the Qiyaoshan fault was characterized by normal activities.The Rongchang earthquake along southern Huayingshan fault was a reverse fault activity with strike-slip component,therefore,the(southern)Huayingshan fault was characterized by reverse activities.On a regional view of focal mechanism,the western part of Chongqing where the Huayingshan fault is located is mainly controlled by compressional stress in rough E–W direction,which is similar to the stress environment in South China.The central and eastern part of Chongqing where the Qiyaoshan fault is located is mainly controlled by compressional stress in rough S–N direction,but the stress field is different from background(rough E–W)stress environment in South China.All these data indicate that the areas from the central and eastern part of Chongqing to Hubei–Hunan plain are in a special dynamic environment.In fact,the areas are in the transition region between two global tectonic domains,i.e.,Tethyan and circum-Pacific tectonic domains.The distinctive present stresses imply that the region from central and eastern Chongqing to Hubei–Hunan plain seems not to be affected by the two global tectonic domains in the present.

关 键 词：震源机制解 应力 七曜山断裂 华蓥山断裂 重庆 

分 类 号：P315.33[天文地球—地震学] P553[天文地球—固体地球物理学]