晋冀豫交界地区地壳三维速度结构与地震分布特征

Three-dimensional velocity structure and seismic distribution characteristics in the juncture of Shanxi,Hebei,and Henan Provinces

利用区域双差层析成像方法,基于2008年10月—2018年6月近震资料,对晋冀豫交界地区记录到的地震事件进行震源位置与P波、S波三维速度结构的联合反演。重新定位后,地震空间位置得到明显改善,浅部的速度结构与地形及沉积层厚度对应较好,研究区内控制性断裂和地震多分布在太行山隆起区的高、低速变化梯级带上。对比分析研究区内不同构造单元及同一构造单元不同深度的P、S波速度异常特征及其与中小地震和历史强震的分布关系,结合研究区内历史强震和现今中、小震分析发震构造及深部孕震环境,为该区未来强震危险区判定提供科学依据。

We applied the double difference tomography method to relocate seismic events and invert crustal velocity structure of the juncture of Shanxi,Hebei,and Henan Provinces using seismic data from October 2008 to June 2018.After relocation,the spatial distribution of seismic events is improved greatly,and the velocity structure at shallow depth coincides well with topography and sedimentary thickness.The control faults and the events of the study area are mostly distributed along the high-low velocity gradient belt of the Taihang mountain uplift area.We analyzed the tomography results and obtained the characteristics of P-and S-wave velocity anomalies among different tectonic units or the same unit but for various depths.Also,we studied the relationship between the velocity anomalies and the distribution of medium-small earthquakes and historical strong events.Combined with the active seismogenic structures and the deep seismogenic environment of historical strong earthquakes and the medium and small earthquakes in the study area,a scientific basis for the determination of future strong earthquake risk areas can be provided.