Synthesis of Three-Component Seismogram Envelopes for Earthquakes Using Scattering Amplitudes from the Born Approximation

Abstract

Figure 2.29 shows that the initial direction of motion of the P-wave, the amplitudes of the direct P- and S-waves, and the high-frequency character of the P- and S-coda envelopes on all three components of motion from a local microearthquake are influenced by the angle between the fault plane and the receiver and the scattering characteristics of the lithosphere. To better understand the effects of scattering on recorded regional seismograms, we desire a method to synthesize threecomponent seismogram envelopes for realistic earthquake sources in an inhomogeneous medium. The simplest way to synthesize seismograms is to sum up all waves scattered by distributed heterogeneities in the time domain. Craig et al. [1991] synthesized the high-frequency seismograms of a local explosion by summing up all singly scattered waves from distributed spherical obstacles; however, this method needs detailed information about the scatterers and considerable computational work.