黄土高原及邻区地壳P波速度结构  

Crustal P-wave velocity beneath the Loess Plateau and its surrounding region

作　　者：方炜[1,2] 白超英[1] 彭建兵[1] 

机构地区：[1]长安大学地质工程与测绘学院,中国西安710054 [2]陕西省地震局,中国西安710068

出　　处：《地震学报》2013年第3期315-327,450,共13页Acta Seismologica Sinica

基　　金：国家自然科学基金重点项目(40534021);国家自然科学基金面上项目(40774020)共同资助

摘　　要：利用地震波走时联合反演算法(改进型最短路径算法)进行三维弯曲地震射线追踪正演,以及共轭梯度法求解带约束的阻尼最小二乘问题进行反演,同时更新速度模型和地震震中位置,结合地方震和区域地震走时资料得到了黄土高原(含汾渭断陷盆地)及邻区地壳三维P波速度结构.其横向变化结果表明,研究区地壳内的P波高速异常区与其内的地震活动构造带相一致,地震多发生在P波高速异常区的边缘或高、低速异常区的交汇处.秦岭山区和鄂尔多斯块体东南区为P波低速异常区.而垂向变化结果则表明研究区存在低速异常区.A simultaneous travel time inversion procedure was developed in col- laboration with a modified shortest path algorithm, which was applied to a bent ray tracing forward calculation. The conjugate gradient algorithm was used to solve a damped least square problem. The crustal P-wave velocity structure be- neath the Loess Plateau and its surrounding regions of China were tomographi- cally imagined down to the depth of 50 km by inverting P wave travel time data from local and regional earthquakes. The result indicates that lateral high veloc- ity anomaly regions generally coincide with the seismically active zones, while vertical velocity variations show existence of a low velocity zone.

关 键 词：三维地震联合反演 地壳P波速度结构 黄土高原 汾渭断陷盆地 

分 类 号：P315.8[天文地球—地震学]