汶川地震强震动地面倾斜研究  

Study of ground surface tilts from strong motion records of the Wenchuan earthquake

作　　者：彭小波 李小军[3,2] 

机构地区：[1]江苏省地震工程研究院,中国南京210014 [2]中国地震局工程力学研究所,中国北京100081 [3]中国地震局地球物理研究所,中国哈尔滨150080

出　　处：《地震学报》2012年第1期64-75,127,共12页Acta Seismologica Sinica

基　　金：国家自然科学基金重大研究计划项目(90715038,91015001);国家科技支撑计划课题(2009BAK55B05)资助

摘　　要：根据三分量强震动传感器水平摆和竖向摆对倾斜的动力响应差异,利用谱比法计算出汶川MS8.0地震中近断层强震动的断层法线方向和平行方向的同震地面倾斜.结果表明,本次地震中强震动观测台处地面倾斜一般小于1°,影响频段主要在0.1Hz以下,发生较大倾斜的台站主要在距地表破裂迹线30km以内,在100km之外或水平向加速度幅值均方根在200cm/s2以下时很少发生0.01°以上的同震地面倾斜.总体上看,上盘区域的倾斜值普遍小于下盘区域,法线方向倾斜值一般大于平行线方向倾斜值.位于前山断裂与中央断裂之间区域的绵竹清平台谱比较低但平缓且频带较宽,可能反应了该区域的运动特殊性,而汶川卧龙台则显示了上盘边缘区域地面倾斜较大.逆冲段与走滑段台站倾斜对比显示,地面倾斜可能受局部场地条件影响较大.Based on the difference of dynamic response to tilts between horizontal pendulums and vertical pendulum, spectral ratio method was applied to estimaion records of the Wenchuan earthquake. The result shows that the ground surface tilts te the coseismic surface tilts deduced from strong motare generally less than 1 degree and mainly appears within 30 km to fault rupture surface traces, while rarely discovered in the area outside 100 km or root-mean squared horizontal peak accelerations are less than 200 cm/se. The frequency band influenced by tilts is less than 0. 1 Hz. In general, tilts in hanging wall is greater than that in footwall in near fault areas, and tilts in normal direction of fault is less than those in parallel direction. The spectral ratio of Qingping station located between central fault and front mount fault is relatively low and stable, which may imply ae special movement feature of the area. The tilts of Wolong station may be controlled by deformation transition from the hanging wall to laterally stationary area. Comparison of tilts between the stations at reverse and strike slip fault segments showed that the tilts may be influenced by local site condition.

关 键 词：强震动 地面倾斜 谱比 倾斜特征 

分 类 号：P315.2[天文地球—地震学]