麦积山石窟近场活动断裂潜在地震变形研究  

Potential seismic deformation of the Majiishan Grottoes induced by near-field active faults

作　　者：亓绚薇 赖天文[1] 石玉成[2] 梁庆国[1] QI Xuanwei;LAI Tianwen;SHI Yucheng;LIANG Qingguo(School of Civil Engineering,Lanzhou Jiaotong University,Lanzhou 730070,Gansu,China;L anzhou Institute of Seismology,CEA,Lanzhou 730000,Gansu,China)

机构地区：[1]兰州交通大学土木工程学院,甘肃兰州730070 [2]中国地震局兰州地震研究所,甘肃兰州730000

出　　处：《地震工程学报》2025年第3期690-699,共10页China Earthquake Engineering Journal

基　　金：国家自然科学基金区域创新发展联合基金项目(U22A20599)。

摘　　要：麦积山石窟近场范围内发育有多条断裂,历史上尤以西秦岭北缘断裂带对麦积山石窟影响最大。为探究近场发震断层对麦积山石窟的影响,在分析西秦岭北缘地区地震地质条件及其潜在地震危险性的基础上,结合断层的弹性位错理论与三维有限元数值模拟方法,以西秦岭北缘断裂带天水—宝鸡段为研究对象,研究7级和7.5级地震下断层左旋走滑活动时,麦积山石窟地区地表的位移与应变分布规律,分析麦积山石窟的潜在地震变形,讨论断裂尺度对地表变形的影响。研究结果表明,天水—宝鸡断裂地震变形以水平剪切为主,垂直形变次要且局部化,高震级使位移和应变量值、范围显著提升。麦积山石窟地区的地震位移、正应变和剪应变随震级的增大而增加,未来地震时石窟的东南方向位移最不利,剪应变为主要风险,可能导致岩体错动或局部剪切破坏。此外,断裂面尺度会影响计算结果,当断裂面深度达到15 km时,地表变形量趋于稳定,这一断裂面深度可作为西秦岭北缘断裂带天水—宝鸡断裂地震模拟参考值。研究结果对麦积山石窟的地震灾害风险评估及防治具有重要参考意义。Multiple active faults are developed in the near field of the Majiishan Grottoes,with the northern margin fault zone of the West Qinling Mountains historically posing the greatest seismic threat.To investigate the impact of near-field seismogenic faults on the Majiishan grottoes,the seismic geological conditions and potential seismic hazards of the northern margin fault zone of the West Qinling Mountains were analyzed in this study.Combining the elastic dislocation theory and the three-dimensional finite element numerical simulation,the displacement and strain distribution patterns on the surface of the Majiishan Grottoes area during left-lateral strike-slip activities along the Tianshui—Baoji segment of the northern margin fault zone of the West Qinling Mountains under M 7.0 and M 7.5 earthquakes were examined.The results reveal that seismic deformation of the Tianshui—Baoji fault is dominated by horizontal shear,with localized secondary vertical deformation.Higher magnitudes significantly increase the magnitude and spatial extent of displacement and strain.In the Majiishan Grottoes area,seismic displacement,normal strain,and shear strain increase with the increase of magnitude.The southeastern direction of the grottoes exhibits the most critical displacement under future earthquakes,with shear strain posing the primary risk for potential rock mass dislocation or localized shear failure.Additionally,fault plane dimensions influence computational results:surface deformation stabilizes when the fault plane depth reaches 15 km,which can serve as a reference value for seismic simulations of the Tianshui-Baoji fault.This study provides critical insights for seismic risk assessment and mitigation of the Majiishan Grottoes.

关 键 词：麦积山石窟 西秦岭北缘断裂 形变场特征 地震变形 

分 类 号：P315.7[天文地球—地震学]