应用地震层析成象技术研究深部速度结构

A Seismic Tomography Study of Deep Velocity Structure

罗马尼亚Ｖｒａｎｃｅａ地震区是大陆上发生与板块碰撞和削减有关的中深源地震活动的地区之一。本文介绍了应用地震层析成象方法研究该地区深部速度结构的成果。在研究中使用了地方和区域地震台所记录的４３３个浅源和中深源地震的到时资料来反演求解深至２００ｋｍ的三维速度结构。在走时和射线路径的计算中利用了有效的三维射线跟踪技术，在反演中采用了ＬＳＱＲ算法。高分辨率的地震层析图象揭示了速度结构的广泛不均匀性。结果表明，地震层析成象技术是研究大陆地球动力学的有力工具。

Seismic tomography was utilized to image deep velocity structure in the Vrancea seismic zone Romania, where intermediate-depth seismicity is associated with subduction and plate collision.We used arrival time data from 433 shallow and intermediate- depth earthquakes recorded by local and regional seismic stations to invert for the three- dimensional (3-D) seismic velocity structure.The travel times and ray paths were calculated by an efficient 3-D ray-tracing technique. The P wave velocity struture was determined from the surface down to a depth of 200 km by using the LSQR algorithm. High-resolution tomographic images reveal a pattern of broad heterogeneity in the velocity structure Our results indicate that seismic tomography can be a powerful tool for understanding continental geodynamics;