利用小震与强震震源机制解反演首都圈现今构造应力场

由于首都圈地区近年来布设了较为密集的地震台网, 使得较小地震震源机制的求解成为可能。 本文收集了首都圈地区近50年来大震震源机制以及2002—2004年中小震震源机制解, 采用对不同震级地震进行加权处理的网格搜索法将强震与小震结合对首都圈地区的现今地壳应力场进行反演。 得到了较为精确的首都圈地区各区域的构造应力场。 结果表明: 北京张家口区, 主压应力轴N(43°～86°)E向; 唐山及邻区,主压应力轴N(38°～86°)E向; 邢台区, 主压应力轴N(79°～81°)E向; 本文反演结果与前人结果相似, 表明了研究方法的正确性, 并揭示了现今首都圈地区应力场的整体一致性和分区差异, 对解释首都圈地区的发震背景和地球动力学研究有一定的参考意义。

Present Tectonic Stress Field in the Capital Region of China Determined from Small and Strong Earthquake Focal Mechanisms

The capital region of China emplaces dense seismic network in recent years, it is possible to solve small focal mechanisms. We gathered large earthquake focal mechanisms in last fifty years and moderate or small earthquake focal mechanisms between 2002 and 2004, and calculated the present tectonic stress field of the capital region by the grid search method, which weighs different sized earthquakes and can improve the accuracy of the stress field inversion. The analysis of inversion results of different subregion show that the direction of the maximum principle compressive stress axe is toward N(43°～86°)E in the Beijing—Zhangjiakou—Datong region, toward N(38°～86°)E in Tangshan area, and toward N(79°～81°)E in Xingtai area. Inversion results of this paper are similar with previous results, and reflect the correctness of the approach. The results reveal the stress field distribution consistency and subregion difference in the capital region, and can provide reference for earthquake mechanism explanation and geodynamics research.