The Effect of Focal Depth and Source Type on Synthetic Seismograms

Abstract

The effects of various parameters such as focal depth, source type, and source-to-receiver distance on the vertical components of Pn, Pg, Lg, and Rg are investigated using synthetic seismograms formed by the summation of P-SV normal modes. The normal mode method of seismogram synthesis is particularly well suited for studies of this type. The calculation of the normal modes, the most time-consuming part of the computations, depends only on the earth model and can be done once. The computation of the synthetic seismograms then requires summation of the individual modes as excited by the source function. The cost of computing the suite of seismograms in this step is due mainly to the inverse Fourier transformation. Summation of normal modes has been successfully used previously to synthesize crustal phases such as the transverse component of Lg (1,2), the transverse component of Sn (3,4) and the vertical component of Pg (5). In this study, we will investigate the source and depth dependence of the vertical component of all of the major crustal phases.