兰州盆地最大潜在地震变形数值模拟  

Potential Earthquake Deformation and Stress Simulation of Lanzhou Basin

作　　者：王爱国[1] 袁道阳[1] 梁明剑 

机构地区：[1]中国地震局地震预测研究所兰州基地,甘肃兰州730000 [2]甘肃省地震局,甘肃兰州730000

出　　处：《西北地震学报》2008年第3期232-238,共7页Northwestern Seismological Journal

基　　金：中国地震局地震预测所基本科研业务专项(2007690);中国地震局兰州地震研究所论文LC2008010

摘　　要：在分析兰州盆地及周边地震构造环境、深部地球物理特征及盆地结构构造特征的基础上,建立了马衔山北缘断层西段发震的三维地震构造模型。采用三维有限元方法计算了该断层段未来发生MS7.0地震在兰州盆地的变形影响。计算结果表明:地震产生的变形及地震应力在兰州盆地区内已有很大程度的衰减,在量值上从盆地西侧到盆地东侧总位移值从1.25 m降至0.3 m;盆地内部最大地震应力则基本保持在0.02 MPa左右,只在盆地边缘及高阶地前缘局部点达到0.2 MPa。地震应变在东、西盆地有明显的分异,但量值总体保持在10-5,只在局部异常点达到10-4,不会在盆地区内形成地表裂缝等破坏,对建筑结构的永久变形影响也较小。但应注意盆地边缘地貌单元分界处与断层附近的局部异常影响及其可能触发的次生灾害。On the bases of the regional seismic tectonics, deep geophysical characters and the basin structure of Lanzhou area, the 3D seismotectonic model is created for earthquake occurring on west part of north Mahanshan fault, and the earthquake deformation influence to Lanzhou basin is calculated on the case of earthquake Ms = 7. The results show that the deformation in Lanzhou basin has certain degree of attenuation and the total displacement of ground surface is from 1.25 m to 0. 3 m from west to east of the basin. The maximum earthquake stress is about 0. 02 MPa in the basin and only reached to 0.2 MPa on parts of the basin edge and front of high terraces. Although the earthquake strain has differentiation in east basin and west basin, the main strain magnitude is 10^-5 and only a few abnormal points reacbs to 10^-4. The deformation would not cause destruction such as ground fracture, and the effect to buildings＇ permanent deformation is weak also. But we should pay attention to the local abnormal effect near the boundaries of geomorphic elements and faults as well as the secondary hazard may be triggered.

关 键 词：地震变形 三维有限元 数值模拟 兰州盆地 

分 类 号：P315.915[天文地球—地震学]