谱比法反演震源谱拐角频率的改进研究  

Improvement in the inversion of corner frequency of thesource spectrum using the spectral ratio method

作　　者：夏晨 利学 周卓群 戚承志 XIA Chen;LI Xue;ZHOU Zhuoqun;QI Chengzhi(School of Civil and Transportation Engineering,Beijing University of Civil Engineering and Architecture,Beijing 100044,China;Beijing Advanced Innovation Center for Future Urban Design,Beijing University of Civil Engineering and Architecture,Beijing 100044,China;Beijing International Scientific and Technological Cooperation Base of Construction of Urban Traffic Infrastructure,Beijing University of Civil Engineering and Architecture,Beijing 100044,China)

机构地区：[1]北京建筑大学土木与交通工程学院,北京100044 [2]北京建筑大学北京未来城市设计高精尖创新中心,北京100044 [3]北京建筑大学城市交通基础设施建设北京国际科技合作基地,北京100044

出　　处：《地震工程学报》2023年第4期954-961,990,共9页China Earthquake Engineering Journal

基　　金：国家自然科学基金(51708018);北京市教委科研项目-科技计划一般项目(KM202010016016);北京建筑大学市属高校基本科研业务费专项资金资助(X18268,X19025)。

摘　　要：由于地震波的信噪比,传播路径效应,震源机制差异和震源过程等因素的影响,传统的谱比法反演的拐角频率结果不精确,离散性大。以谱比法为基础,引入Bootstrap重采样法,KolmogorovSmirnov检验以及谱比趋势检验的筛选方法,对谱比法的反演结果进行精度评定和筛选,提高谱比法反演的拐角频率精度。将此方法应用于汶川地震余震的拐角频率、地震辐射能量、辐射效率以及能矩比等震源参数反演,建立拐角频率与地震矩之间的对应关系,验证谱比法以及三种筛选方法的可靠性。汶川地震余震震源参数反演结果表明,汶川地震余震的拐角频率与地震矩对应关系M0∝fc-3.295±0.25存在与自相似关系M0∝fc-3偏离现象。在地震释放能量方面,存在能矩比随地震矩增大而增大,以及大地震的辐射效率大于小地震的现象。Corner frequency is an important dynamic parameter in seismic source physics.Accurate calculation of the corner frequencies is important for obtaining other seismic source parameters and improving the source spectrum model.However,corner frequency inversion results by the traditional spectral ratio method are inaccurate and discrete due to the signal-to-noise ratio of seismic waves,propagation path effects,differences in source mechanisms,and source processes of earthquakes.In this work,we utilized the spectral ratio method to estimate the corner frequency and implemented three tests(Bootstrap resampling method,Kolmogorov-Smirnov test,and spectral ratio trend test)to evaluate the calculated corner frequencies.These three tests can improve the accuracy of the corner frequencies estimated by the spectral ratio method.The spectral ratio method and these three tests were validated by calculating the seismic source parameters of the aftershocks of the Wenchuan earthquake from May 12 to September 12,2008.We obtained the corner frequency f c,radiation energy E R,radiation efficiencyηR,and energy-moment ratio e of aftershocks with magnitude 3.7-6.5.According to the calculated results,the relationship between the corner frequency and the seismic moment can be expressed as M 0∝f-3.295±0.25 c,which is not in agreement with the self-similarity law M 0∝f-3 c.The seismic radiation energy increases with the earthquake magnitude.When the magnitude increases from 3.7 to 6.5,the energy-moment ratio e also increases from 8×10-6 to 5×10-5,and the radiation efficiencyηR increases from 0.32 to 0.9.If the self-similarity law holds,then the energy-moment ratio e and the radiation efficiencyηR should be constant.The inversion results of source parameters of Wenchuan earthquake aftershocks show that in terms of the energy released by earthquakes,the energy-moment ratio increases with the seismic moment,and the radiation efficiency of large earthquakes is greater than that of small earthquakes.

关 键 词：谱比法 BOOTSTRAP方法 拐角频率 地震矩 地震辐射能量 能矩比 

分 类 号：P319[天文地球—固体地球物理学]