重庆浅层S波速度结构研究  

Shallow S-wave velocity structure in Chongqing area

作　　者：董蕾 沈旭章 陈丽娟 Dong Lei;Shen Xuzhang;Chen Lijuan(Chongqing Earthquake Agency,Chongqing 401147,China;School of Earth Sciences and Engineering,Sun Yat-sen University,Guangzhou 510275,China)

机构地区：[1]重庆市地震局,重庆401147 [2]中山大学地球科学与工程学院,广州510275

出　　处：《地震学报》2022年第6期998-1006,共9页Acta Seismologica Sinica

基　　金：中国地震局震情跟踪项目(2020010129)资助.

摘　　要：基于重庆台网及邻区固定台站自2011年1月至2018年10月观测到的远震波形记录,利用接收函数直达P波振幅约束浅层结构的方法计算了重庆及周边地区台站下方浅层S波速度结构,结果表明:重庆浅层S波速度结构与盆山构造明显相关,盆地内表现为低速异常,与沉积层特征相对应,大巴山、大娄山区域则表现为相对高速的特征;华蓥山断裂S波速度高于断裂两侧的沉积层速度,表现出四川盆地沉积层中间薄两边厚的特点;华蓥山以东的川东地区多为套滑脱层构造,其浅层S波速度表现为低速异常。最后讨论了2010年以来重庆5次显著地震的孕震环境:川东滑脱构造地区的垫江M_(S)4.4地震和石柱M_(S)4.5地震与该区明显的低速异常有关;荣昌M_(S)4.7和M_(S)4.8地震的震源区无明显的高低速特征,可能与注水相关;武隆M_(S)5.0地震发生在高低速交界部位的有利于积累应变的高速体一侧。Based on the teleseismic waveform data recorded at permanent stations in Chongqing and its adjacent area from January 2011 to October 2018,the shallow S-wave velocity structure beneath the stations of Chongqing and its surrounding area is calculated by the method to constrain shallow structure based on direct P-wave amplitude in receiver functions.The results indicated that,the velocity structure of shallow S-wave in Chongqing is obviously related to the basin mountain structure,the low velocity anomaly in the basin corresponds to the characteristics of sedimentary layer,and the Daba mountain and Dalou mountain regions show relatively high velocity anomalies.The S-wave velocity of Huayingshan fault is higher than that of sedimentary layers on both sides of the fault,implying that the sedimentary layers in Sichuan basin are thin in the middle and thick on both sides.Finally,we discussed the seismogenic environment of five earthquakes in Chongqing since 2010.The Dianjiang M_(S)4.4 earthquake and the Shizhu M_(S)4.5 earthquake located in the east Sichuan detachment structure area are related to the obvious low velocity anomaly.The Rongchang M_(S)4.7 and M_(S)4.8 earthquakes have no obvious characteristics of high or low velocities,which may be related to water injection.The Wulong M_(S)5.0 earthquake occurred on the high velocity body side that is conducive to strain accumulation of the high and low velocity junction.

关 键 词：重庆地区 接收函数 浅层S波速度结构 孕震环境 

分 类 号：P315.3[天文地球—地震学]