2006年文安Mw4.9级地震的有限震源波形模拟研究

2006年7月4日发生在河北文安的M_w4.9级地震，由于没有地表破裂并缺乏能够精确定位的余震序列，从而在地震发震构造的确定上存在困难.本文利用首都圈地震台网9个台站的Z分量数字波形记录，通过与有限震源模型的理论波形模拟结果比较，能够快速分辨发震断层面及破裂扩展方式，同时对震源运动学参数提供一定约束.结果显示，在文安地震震源机制解的两组共轭节面中，走向110°、倾角65°、滑动角8°的节面更有可能代表真实的发震面；破裂扩展方式为一向西扩展的单侧破裂.这一结果与本区域构造应力研究及块体相对运动方向观测结果一致.本文的工作，为中等震级地震发震构造的快速确定提出了一种简单而有效的方法.

Finite-source waveform modeling of the 2006 Wen′an Mw4.9 earthquake

Based on Z-component records of 9 stations in Beijing metropolitan digital Seismic Network (BSN), we analyzed the finite-source effect of the 2006 Wen′an M_w4.9 earthquake, identified the actual rupture plane, and discussed the tectonic implications of our results. Due to the absence of surface rupture, the lack of connection between the source and known faults in the region, and the paucity of aftershocks, it has been difficult to identify the actual rupture plane of the Wen′an earthquake. To tackle this problem, here we present a simple and efficient approach to resolving the fault-plane ambiguity and probing the kinematic source properties by modeling the waveforms in realistic three-dimensional structures from finite-source models. Between the two conjugate planes in the focal mechanism solution, we found that the one with a 110° strike is the likely rupture plane. We also determined that the overall source process is a westward unilateral rupture. These results are consistent with regional tectonic stress trend and the observed relative movement of tectonic blocks.