基于加速度包络的芦山地震高频辐射反演

Estimation of high-frequency wave radiation areas of Lushan earthquake by the envelope inversion of acceleration seismograms

基于经验格林函数和加速度包络,利用差分进化法反演了芦山地震断层面上高频地震波(1~10 Hz)辐射区域,其高频地震波的辐射强度利用震源时间函数的幅值表示。结果表明,芦山地震断层面上高频辐射分布很不均匀,其中凹凸体部分是高低频辐射最强的区域,另外,凹凸体周边以及断层破裂停止的区域也存在较强的高频地震波辐射,而这些区域的低频地震波辐射则很弱。这表明芦山地震地震波辐射过程是极其复杂的,研究结果对宽频带地震动模拟芦山地震震源模型的建立具有一定的应用价值。

Based on the empirical Green’s function and the envelope of acceleration seismograms,the high-frequency( 1 ~ 10 Hz) wave radiation areas on the Lushan earthquake fault plane was inversed by the differential evolution method,radiation intensity of high frequency seismic waves was expressed by the mean value of the 1 ~ 10 Hz Fourier amplitude spectrum of the source time function. The results indicate that the high-frequency wave radiation areas on the Lushan earthquake fault plane were significantly nouniform,with the strongest high and low frequency waves radiated in the asperities. In addition,the high-frequency seismic waves also radiated in the areas close to the boundaries of the asperities and the areas of the fault boundaries where rupture stopped. However the low frequency seismic waves in these regions are very weak. The result indicates that the seismic wave radiation process of Lushan earthquake is very complicated. The results also have some application value in the establishment of the source model of Lushan earthquake in the broadband ground motion simulation.