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论文类型：期刊论文

发表时间：2013-06-01

发表刊物：EARTHQUAKE ENGINEERING AND ENGINEERING VIBRATION

收录刊物：SCIE、EI、CSCD

卷号：12

期号：2

页面范围：185-194

ISSN号：1671-3664

关键字：non-isotropic scattering; coda wave; envelope broadening; energy transport theory (radiative transfer theory); directional scattering coefficient; ground motion

摘要：Based on the formulation of a multiple non-isotropic scattering process, a characteristic source time is introduced to define the initial impulse width of energy density at the source. An analytical expression of the initial intensity spectral density of a seismic wave is incorporated into the integral equation of seismic wave energy density. And, a recursive formula of Green's function is derived to obtain the higher order Green's function, which is included to describe the stronger non-isotropic scattering process. Then, the effect of the scattering pattern on the energy density envelope is investigated by the modified scattering theory. Significant differences are found in the decay of the energy density envelopes with distances using different scattering patterns. The envelope synthesized by the forward dominated scattering pattern is larger than the results obtained by the isotropic and backward dominated scattering pattern. Different scattering patterns are also used to fit the observation data from the aftershocks of the 2008 Wenchuan earthquake. It is concluded that the envelopes synthesized by the forward scattering pattern can match the data better than the isotropic and backward dominated scattering cases, and a new interpretation of the coda wave is given. Finally, using the forward dominated scattering pattern, the envelope broadening of the observed data is reproduced.