The Effect of Multiple Anisotropic Scattering Pattern on S Wave Energy Density Envelope


Based on the multiple anisotropic scattering theory, we reevaluate the spherical harmonic series expansion of directional scattering coefficient. A characteristic source time is introduced to define the initial impulse width of energy density at the source. We use an analytical expression of the initial spectral energy intensity in the integral equation of seismic wave energy density at any given frequency. The modified integral equation is solved by a discrete wave number method. Based on this solution, we investigate the effect of scattering pattern on S wave energy density envelope. And the numerical simulation shows that after the S arrival time the difference of the energy density envelope between the multiple anisotropic scattering pattern and the isotropic scattering pattern increases with distances. Using forward anisotropic scattering pattern, we successfully reproduce the common decay of the seismic coda wave energy density envelopes at different hypocentral distances. For the same pattern, the S wave energy density envelope broadens with increasing hypocentral distance. Finally, we verify the forward anisotropic scattering pattern with the observation from the aftershock of the 2008 Wells, Nevada earthquake in USA.


Civil, Architectural and Environmental Engineering

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Article - Journal

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Publication Date

01 Jun 2012