冀南地区速度结构层析成像分析  

Velocity structure tomography analysis in southern Hebei Province

作　　者：王时 周依 王思思 刘晓磊 Wang Shi;Zhou Yi;Wang Sisi;Liu Xiaolei(Hebei Hongshan National Observatory on Thick Sediments and Seismic Hazards,Hebei Xingtai 054000,China;Hebei Earthquake Agency,Hebei Shijiazhuang 050021,China)

机构地区：[1]河北红山巨厚沉积与地震灾害国家野外科学观测研究站,河北邢台054000 [2]河北省地震局,河北石家庄050021

出　　处：《地震科学进展》2024年第8期506-514,522,共10页Progress in Earthquake Sciences

基　　金：河北省地震科技星火计划(DZ2023120700006,DZ2024111400001,DZ2024112100001)资助。

摘　　要：克拉通的破坏是地球物理学家重点研究的对象之一。经由中国地震台网查询得知,近年来冀南地区中小地震相较以往频繁发生,为了探查冀南地区地壳结构不稳定的原因,本文基于中国地震台网记录到的P波到时资料,对研究区的地震进行精定位,并利用P波的震相数据对地壳速度结构进行双差层析成像:发现精定位后的震源主要分布在地壳5~15 km深度,主要集中在断层附近;在速度结构方面,地震走时残差均方根的总体均值由0.81 s下降至0.36 s,地震更容易发生在高速区的边缘过渡带上;在邯郸和邢台等地区的壳幔结合处存在低速异常区,莫霍面和上地幔可能受到岩浆等热流物质上涌,侵入地壳,发生化学反应,导致岩石圈的减薄破坏,致使地壳结构趋于不稳定状态,进而对浅层地震的孕育创造了有利条件。The destruction of cratons is one of the key research objects of geophysicists.According to China Earthquake Networks Center,small and medium-sized earthquakes have occurred more frequently in southern Hebei in recent years than before.In order to explore the reasons for the instability of the crustal structure in southern Hebei,in this paper the earthquakes are precisely located based on the P-wave arrival time data recorded by China Earthquake Networks Center,and the double difference tomography of the crustal velocity structure is performed by using the P-wave seismic phase data.It is found that the sources after fine location are mainly distributed in the crust depth of 5~15 km,mainly near the faults.In terms of velocity structure,the mean RMS value of seismic travel time residuals decreases from 0.81 s to 0.36 s,and the earthquakes are more likely to occur in the transition zone at the edge of the high-speed region.There is a low-speed anomaly zone at the junction of the crust and mantle in Handan and Xingtai.The Moho surface and upper mantle may be upwelling by hot flow materials such as magma,intruding into the crust and undergoing chemical reactions,leading to the thinning and damage of the lithosphere,resulting in an unstable crustal structure and creating favorable conditions for shallow earthquakes.

关 键 词：双差层析成像 岩石圈破坏 三维速度结构 冀南地区 

分 类 号：P315.31[天文地球—地震学]