地震动峰值加速度衰减关系对中国西部地区的适用性分析

Analysis and Application of Attenuation Relationships for Peak Accelerations of Ground Motion in Western China

地震动参数衰减关系描述了地震动参数随震级和距离等因素的变化情况,选取合适的地震动衰减关系是地震危险性分析中确定工程场地地震动参数的关键环节。本文收集、整理和分析了中国西部地区2012年3月9日-2017年9月16日间发生的42次地震事件中获取的强震动记录资料,并选择了3个国际上基于不同地区强震动记录数据建立的地震动加速度衰减关系(ASB11、SCEMY97和LLCS11),开展了加速度衰减关系计算结果与中国西部强震动记录值的对比研究。比较了衰减关系峰值加速度的预测中值与实际记录值之间的差异,并分析了其残差随震级和距离的变化。得到了以下结论:①相比于SCEMY97和LLCS11,ASB11更适合于中国西部地区;②研究中国西部地区的衰减关系时,有必要考虑高频地震动的震级饱和现象。同时,对于如何修正已有衰减关系以使其更适合于中国西部地区给出了相应的建议。

The ground motion attenuation relationship depicts how ground motion parameters vary with factors such as magnitude and distance. It is critical to choose an appropriate attenuation relationship in determining the ground motion parameters for engineering sites in seismic hazard analysis. In this study, ground motion records from 42 earthquake events happened from 9 March 2012 to 16 September 2017 in western China were collected, sorted and analyzed. Three attenuation relationships for peak accelerations(ASB11, SCEMY97, LLCS11) worldwide, built with data from different regions, were compared with these record data. Through comparing the peak accelerations calculated by the three chosen attenuation relationships with the recorded peak accelerations, and analyzing the relationships between residuals and magnitude and distance, we conclude out that(1) ASB11 works better for western China than SCEMY97 and LLCS11;(2) the magnitude saturation of high-frequency ground motions needs to be considered in developing attenuation relationship for western China. Moreover, suggestions were made on the revision of the attenuation relationships so that they might work better for western China.