安徽中部地区上地壳二维Pg波速度成像分析  

Analysis on the 2-D Pg Velocity Structure Tomography of Upper Crust in Central Anhui Province

作　　者：陈昊 洪德全[3] 李红星[2] 陈德兴 吴从辉[2] 丁煜晖 CHEN Hao;HONG Dequan;LI Hongxing;CHEN Dexing;WU Conghui;DING Yuhui(Chuzhou Earthquake Agency, Chuzhou 239000, Anhui, China;Anhui Earthquake Agency, Hefei 230003, Anhui, China;East China University of Technology, Nanchang 330013, Jiangxi, China)

机构地区：[1]滁州市地震局,安徽滁州239000 [2]东华理工大学,江西南昌330013 [3]安徽省地震局,安徽合肥230003

出　　处：《地震研究》2018年第1期118-124,共7页Journal of Seismological Research

基　　金：国家自然科学基金项目(41364004、41104073); 安徽省科技攻关计划项目(1301042118); 安徽省地震科研基金青年项目(20160610); 安徽省地震局科研合同制课题(201501)联合资助

摘　　要：利用1976—2014年安徽、江苏、河南、浙江省56个台站记录的近震数据,共提取4 922条Pg波震相走时数据,对安徽中部地区上地壳速度结构进行了二维层析成像反演。反演结果显示:安徽中部地区Pg波速度为6.50 km/s,其横向速度变化为-0.24~0.24 km/s,研究区速度异常分布范围较好地吻合于地表构造单元形态,速度分布特征还反映出不同构造单元在地质演化中存在构造机理和物质组成方面的耦合现象。大别山高压、超高压变质带下方不存在大规模的高速体。"霍山窗"等几个地震高发区均位于高、低速度异常区的边界地带,说明地壳速度的转换带亦是构造上的不稳定带,易于发生应力的转换和能量集聚,造成该地区小震频发或引发中强地震。A total of 4 922 Pg arrival times from 1976 to 2014 that were extracted from 56 stations in Anhui,Jiangsu,Henan and Zhejiang Provinces,which were used for 2-D seismic tomography inversion in the upper crust velocity structure of the central Anhui Province. The results demonstrate that the Pg velocity in the central Anhui is about 6. 50 km/s and the lateral velocity varies from -0. 24 km/s to 0. 24 km/s. The distribution of velocity anomalies in the study area is consistent with the surface tectonic units,and the characteristics of velocity distribution further reflect a coupling phenomenon between structural mechanism and material composition of the different tectonic units in geological evolution. The results confirm that high speed body on a large scale under the high pressure or ultrahigh pressure metamorphic belts do not exist in the Dabie Mountains. Furthermore,the high-frequent earthquake region,for instance,Huoshan seismic window,located in the border zone of high and low velocity anomaly area. This illustrates that the frequent occurrence of earthquake swarm or moderate earthquake in the area indicates that the transition zone of seismic velocity underground is prone to stress conversion,energy accumulation,and instability belt in structural geology as well.

关 键 词：层析成像 Pg波 上地壳 速度结构 安徽中部地区 

分 类 号：P313.2[天文地球—固体地球物理学]