上月壳中的散射引起月震尾波的数值模拟研究

发布时间：2018-06-16 23:52

本文选题：散射 + 月震尾波　；参考：《地球物理学报》2015年05期

【摘要】：在阿波罗月震记录中普遍存在着强烈持久的尾波信号,这样的波形特征无法用均匀分层月球模型解释.一个普遍被接受的解释是月震尾波由月球浅层结构对月震波的散射引起.我们采用基于交错网格的伪谱和有限差分混合方法模拟研究非均匀上月壳对月震波的散射效应,在此基础上解释月震尾波的形成机制,并估计出上月壳速度扰动的强度.我们发现,在均匀分层模型基础上,进一步考虑上月壳中的非均匀结构对月震波的散射效应,能有效地解释月震信号中强烈持久的尾波.我们认为月震尾波可能是由上月壳中的低波速、低衰减和散射这三个因素的共同作用所引起.采用不同的扰动标准差模拟上月壳的非均匀性,并比较模拟波形与真实月震图的相似程度,我们发现上月壳中速度扰动的标准差应该在3%到5%之间,很可能接近于3%.
[Abstract]:Strong and persistent coda signals are commonly found in the Apollo lunar seismic records, which can not be interpreted by the uniform stratified lunar model. A generally accepted explanation is that the coda of a lunar earthquake is caused by the scattering of the wave by the shallow structure of the moon. In this paper, we use the mixed pseudo-spectral and finite-difference method based on staggered grids to simulate the scattering effect of the inhomogeneous shell to the lunar seismic waves, and then explain the formation mechanism of the coda waves of the lunar earthquakes and estimate the intensity of the velocity disturbances of the lunar shells. We find that on the basis of homogeneous stratification model, the scattering effect of non-uniform structures in the lunar shell on the monthly seismic wave can be considered further, which can effectively explain the strong lasting coda in the lunar seismic signal. We think that the coda of a lunar earthquake may be caused by the interaction of three factors, namely, low wave velocity, low attenuation and scattering in the shell of last month. Using different disturbance standard deviations to simulate the inhomogeneity of the shell and compare the similarity between the simulated waveform and the real monthly seismogram, we find that the standard deviation of velocity disturbance in the shell should be between 3% and 5%, which is likely to be close to 3%.
【作者单位】：北京大学地球与空间科学学院地球物理系;日本东京大学地震研究所;
【基金】：国家自然科学基金(41374046,41174034)资助
【分类号】：P184

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