DEPSCOR 95 Calibration of Nuclear Monitoring and Development of Regional Velocity Structure Using Unique Seismic Data Sets from Former Soviet Union
Abstract
We study long seismic profiles in the Former Soviet Union that are sourced by a number (1-4) of Peaceful Nuclear Explosions (PNE's). These profiles offer explosions in different geologic materials that generate strong seismic waves that propagate through different tectonic provinces, affecting their propagation characteristics. The ultra-long Deep Seismic Sounding (DSS) profile "Quartz' crosses 6 major geologic provinces in Eurasia and is sourced by 3 nuclear (PNE) and 48 chemical explosions. High velocity (8.4 km/sec) uppermost mantle is found under the Mezenskaya depression and under the east flank of the Urals. One almost continuous upper mantle boundary occurs at 65 to 80 km depth, and another with an approximately 40-km thick LVZ occurs at 120-140 km depth. The shallow upper mantle blocks and the two extensive interfaces indicate strong upper mantle heterogeneity imaged by this unique profile. Using travel-time modeling techniques, we associate the teleseismic P(sub n) with whispering gallery modes traveling within the top 160 km of the mantle. The long incoherent coda of this phase results from scattering and from reverberations of seismic waves within the crust. We examine the unusually strong and extensive coda of the long-range P(sub n) interpreted as a whispering gallery, phase propagating to beyond 3000 km. Such an extensive coda is inherent not only to WG but to all other P-wave phases and can be explained by crustal scattering. The long coda is a result of excitation of short-period scattered waves within the crust by the waves incident from the mantle, or, conversely, by generation of mantle phases from crustal guided waves within the source region. Seismic records from nuclear explosions recorded by Deep Seismic Sounding profiles provide valuable information about the propagation of regional and teleseismic S waves and L(sub g) phases across a variety of tectonic structures of Northern Eurasia.
Document Details
- Document Type
- Technical Report
- Publication Date
- Feb 02, 2001
- Accession Number
- ADA387885
Entities
People
- Scott B. Smithson
Organizations
- University of Wyoming