汶川8.0级地震断层下盘基岩衰减关系分析

Footwall attenuation relationships of Wenchuan 8.0 earthquake

选取汶川8.0级特大地震位于断层下盘中的32个台站的强震记录,其中20个为土层台,12个为基岩台。首先,利用一维等效线性方法从土层台水平向强震记录反演出基岩水平向地震时程。随后进行了回归统计分析,给出了此次地震的下盘基岩水平向地震动峰值加速度和反应谱衰减关系。最后将所得结果与其他衰减关系对比分析,通过分析得出所得衰减关系揭示了汶川地震的下盘基岩衰减特性,该衰减关系是合理的,为分析汉源烈度异常确定输入地震动提供了基础数据。

Strong motion records at 32 observation stations from Wenchuan 8. 0 earthquake in 2008 were selected,in which 20 observation stations site conditions are soil and the others are bedrock. First,we inversed horizontal earthguake time history of the bedrock from horizontal strong motion records of the observations on soil site by use of 1-D equivalent linearization wave motion method. Then,regressive statistical analysis was carried out to give the attenuation relationship of peak horizontal seismic acceleration and response spectrm of footwall bedrock of the earthguake. Finally,The attenuation relationships were compared with that from other analyes. Results show that the attenuation models propased in this paper reveal characteristics of footwall bedrock attenuation,they are reasonable.It may provide basic data for determining the input ground motion that is used for analysis of Hanyuan abnormal intensity.