河北省南部及邻区地壳P波速度结构三维反演

1980—2012年河北省及邻区测震台网地震记录，使用了河北省南部及邻区（34.0°—38.0°N，112.0°—118.0°E）63个固定地震台站和4 540个地震事件，得到27 709条P波到时数据，采用速度结构与地震位置联合反演的方法，获得研究区内地壳P波三维速度结构，重新确定中小地震震源位置。速度结构揭示：研究区域内地壳的P波速度结构存在明显的横向不均匀性，在10—25 km深度上横向不均匀性更加显著；大地震基本发生在速度异常体或高低速交界区域。地震重新定位结果显示：地震P波走时均方根残差（RMS）从1.68 s降到0.82 s；地震呈明显条带状分布，震源深度与地质构造年代具有一定负相关性。

Three-dimensional inversion of crustal P wave velocity structure in the south of Hebei and its adjacent areas

In this paper, using 27 709 seismic travel-time data of 4 540 earthquake events recorded by 63 seismic stations of Hebei Seismic Network and its adjacent areas (34° to 38°N and 112° to 118°E) in 1980-2012, the hypocentral distribution and velocity structure are obtained with simultaneous inversion method. The velocity structure reveals that the P wave velocity in the crust of study area is obvious lateral inhomogeneity, and shows more significant lateral heterogeneity in the depth of 10-25 km, and earthquakes occurred in abnormal high speed area or the border of higher and lower speed areas. The relocation results show that the root mean square residual (RMS) of the seismic P wave travel time drops from 1.68 s to 0.82 s. The earthquakes show obvious strip distribution, and the depths of the sources have a negative correlation with the geological age.