Source Contributions at Regional Distances
Abstract
In order to quantify the effects of different components of the explosion source function on far regional seismograms (900-2000km) a one- dimensional velocity model is developed for seismic waves traveling across the Basin and Range. This model is constrained by broadband data recorded at the Lajitas seismic station. Complete synthetic seismograms are developed for the model utilizing the extended reflectivity technique. Pg, Pn, mantle P, Lg and surface waves are included in the data as well as in the synthetics. The P velocity model follows closely that of Olsen et al. (1980,1) developed from shorter offset data. The lack of Sn in the observational data requires a thin mantle S lid not included in these earlier models. The complete set of synthetics replicate the transition of crustal P energy to mantle P around 900km, the rapid decay of Pg beyond 1000km, the lack of Sn energy, and the lower frequency content of Lg relative to the body wave arrivals. This wave propagation model is used to quantify the source effects from an explosion and spall source function. The explosion source is much less sensitive to depth of burial differences than the spall source. Spall and explosion source parameters constrained by near source data indicate that the importance of spall to the Lg phase is source time function dependent. If the peak of the spall source falls outside the low frequency window for Lg, then it has negligible contribution to the regional waveforms.
Document Details
- Document Type
- Technical Report
- Publication Date
- May 14, 1991
- Accession Number
- ADA240859
Entities
People
- Brian Stump
- Karl Koch
- William Soroka
Organizations
- Southern Methodist University