Calculation of Source and Structure Parameters at Regional and Teleseismic Distances
Final technical rept. 1 Jan 1983-3 Mar 1985
PENNSYLVANIA STATE UNIV STATE COLLEGE COLL OF EARTH AND MINERAL SCIENCES
Pagination or Media Count:
Teleseismic SV waves have been generally ignored in wave propagation and source studies because of known complications in wave propagation for structure near the source and near the receiver. The validity of common optic ray and WKBJ seismogram methods for computing SV synthetic seismograms is examined by computing synthetic seismograms using these techniques and comparing them to SV synthetics produced from a wavenumber integration technique. Both ray methods give a poor approximation to the wave propagation for distances less than 60 deg. Diffracted Sp and the SPL wave interfere with near source phases, such as S, pS, and sS for a shallow seismic source, producing anomalously high amplitudes and complex waveforms in agreement with observational experience. Because of the Moho Sp and diffracted Sp phases, the vertical component of motion shows greater distortion, relative to the ray theory result, than does the radial component of motion. Ray theory appears to be appropriate for the initial 20 seconds of the SV wavetrain from a shallow source for ranges greater than 60 deg. SV waves from deep sources are less affected by diffracted Sp and SPL than SV from shallow sources.
- Seismic Detection and Detectors