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合理地估计汶川破坏区域的地震动有助于地震灾害的研究.通过利用芦山地震记录建立的加速度包络衰减关系和汶川地震近场30个台站的加速度包络,基于线源模型,采用差分进化方法反演了汶川地震断层面上高频(>1Hz)辐射区域分布.结果表明:断层面上高频辐射分布很不均匀,辐射较强的区域主要位于:(1)产生较大地表破裂的映秀、北川和南坝区域;(2)映秀和北川等凹凸体的周边区域,包括震中东北侧60~90km区域、北川和南坝东北侧30km处;(3)断层破裂停止的东北端约30km长的区域.其中,破裂贯穿到地表的映秀、北川和南坝是低频和高频辐射都很强的区域.对于无观测记录场点,选择其临近且场地条件类似的台站加速度提取平稳随机过程,结合高频辐射分布和衰减关系得到的包络,合成了加速度时程,可为汶川地震结构震害分析提供地震动输入.
A reasonable estimation of ground motion in the Wenchuan earthquake area is helpful for the study of earthquake disaster.By using the acceleration envelope decay relationship established by Lushan seismic records and the acceleration envelope of 30 stations in the near field of Wenchuan earthquake, The distribution of high frequency (> 1 Hz) radiation on the fault plane of Wenchuan earthquake is retrieved by the evolutionary method. The results show that the distribution of high frequency radiation on the fault plane is very uneven, and the areas with strong radiation are mainly located in: (1) Large surface rupture Yingchuan, Beichuan and Nanba areas; (2) The surrounding areas of the asperity such as Yingxiu and Beichuan include the area of 60 ~ 90km on the northeastern side of the epicenter at 30km northeast of Beichuan and Nanba; (3) the northeast end of the fault rupture 30km long, of which Yingxiu, Beichuan and Nanba, which have been ruptured to the earth’s surface, are areas where both low-frequency and high-frequency radiation are very strong.For unrecorded sites, the station accelerations with similar site conditions are selected and extracted smoothly Stochastic process, combined with the envelope obtained by the relationship between the distribution and attenuation of high-frequency radiation, the acceleration time history is synthesized, which can provide input of seismic motion for structural damage analysis of Wenchuan earthquake.