论文部分内容阅读
岩石的非线弹性响应在实验室中已被广泛地观测到,但在文献中却鲜有地震学研究方面的报道,尽管这是观测到这种特征的最自然的环境。由于难以获得非线性波传播问题的解析解,因此需要使用近似方法。显然,地震波在均匀的非线弹性介质中传播时将受到非线性的扰动。这种扰动可看作是时空中初至波能量散射和传播、产生地震尾波之源。这在某种意义上类似于非均匀性效应。由非线性引起的地震尾波性质与非线性大小以及地震矩有关。我们使用一种扰动方法计算散射波的振幅,并说明该方法能相当好地描述实际地震尾波的主要特征。
The nonlinear elastic response of rocks has been widely observed in the laboratory, but few seismological studies have been reported in the literature, although this is the most natural environment in which this feature is observed. Since it is difficult to obtain an analytic solution to the nonlinear wave propagation problem, an approximation method needs to be used. Obviously, seismic waves will be disturbed nonlinearly when propagating in a uniform nonlinear elastic medium. This perturbation can be seen as the scattering and propagation of the first-arrival wave energy in space-time, resulting in the source of the earthquake wake. This is in a sense similar to the effect of inhomogeneities. The nature of the earthquake wake caused by nonlinearity is related to the nonlinear magnitude and seismic moment. We use a perturbation method to calculate the amplitude of the scattered wave and show that the method can fairly well describe the main features of the actual seismic coda.