首都圈地区横波分裂与地壳应力场特征  

Shear wave splitting and the features of the crustal stress field in the Capital Circle

作　　者：赖院根[1] 刘启元[1] 陈九辉[1] 刘洁[1] 李顺成[1] 郭飙[1] 黄志斌[2] 

机构地区：[1]中国地震局地质研究所,北京100029 [2]中国地震台网中心,北京100036

出　　处：《地球物理学报》2006年第1期189-196,共8页Chinese Journal of Geophysics

基　　金：国家重大基础研究发展规划项目(G1998040702);中国地震局监测预报司联合资助.

摘　　要：利用宽频带流动地震台阵和首都圈固定台网记录到的近震波形数据,研究了首都圈地区(38·6°N^41·0°N,115·0°E^119·7°E)的横波分裂,给出了快波偏振优势方向的场分布,讨论了首都圈地区的应力场特征.在此基础上,采用二维线弹性有限元数值模拟方法,探讨了断层不均匀滑动对区域构造应力场的影响.结果表明:(1)首都圈地区的应力场整体特征表现为NE向的背景应力场和受张家口-蓬莱断裂带控制的NW向的局部应力场;(2)在研究区域的西半部分和中部,最大主压应力方向为NE60°~70°,在唐山大震区及其东部区域,最大主压应力方向近WE向;(3)首都圈地区的局部应力场最大主压应力方向比较一致,基本上都与张家口-蓬莱断裂带走向平行,为120°~130°;(4)首都圈区域内断层的存在及其郴均匀滑动是研究区内出现大量局部应力场的一个重要原因,张家口-蓬莱断裂带对首都圈局部应力场起着重要的控制作用.In recent years, much attention has been paid to the shear wave splitting caused by the medium cracks. In this study we investigate the S-wave splitting at the stations of the Capital Circle area from the local event data recorded by the permanent and movable seismic network. In this presentation we give the fast polarization directions and the maximal compressive stress direction at the stations in the Capital Circle. The 2- D numerical modeling in terms of the finite element technique demonstrates that the crustal stress field of the Capital Circle can be separated into the NE trending regional stress field and the NW trending local stress field controlled by the Zhangjiakou-Penglai faults. The direction of the maximal principal compressive stress nearby Beijing and Tianjin is toward NE60° - 70°, and that nearby Tangshan and its eastern side is toward the EW direction. For the local stress field, the direction of the maximal principal stress is toward 120° -130°, which is roughly parallel with the strike of the Zhangjiakou-Penglai faults. Our numerical modeling demonstrates that the local crustal stress field in the Capital Circle is caused mainly by the Zhangiiakou-Penglai faults.

关 键 词：首都圈 横波分裂 地壳应力场 

分 类 号：P315[天文地球—地震学]