Analysis of Numerical Seismic Source Functions by Finite Difference Method

Abstract

The finite difference synthetic seismograms are tested for a number of seismic sources to understand their stability characteristics. Processing techniques such as frequency filtering and gain application are applied to improve the model response. The grid dispersion due to high frequencies contained in source appears to be controllable by high cut filtering the model output. A single velocity distribution model is used to prepare synthetic seismograms with different source functions. The results seem to be in agreement with the previous work. The output of modeling algorithm gives correct arrival times but when the model becomes unstable, the relative amplitude information of different arrivals seems to be lost. The use of different seismic source wavelets with same central frequency indicates that model stability and numerical anisotropy also depend on the pulse shape or phase characteristics of the source. From the present study it is concluded that in addition to previous work, which showed the numerical stability a frequency dependent phenomenon, it also depends on the phase spectrum of the input source wavelet.