Database of Deep Seismic Sounding Peaceful Nuclear Explosion Recordings for Seismic Monitoring of Northern Eurasia

摘要

The database of seismic recordings of Peaceful Nuclear Explosions (PNEs) at the University of Wyoming now includes 19 PNEs recorded along 7 long- range refraction/reflection profiles: QUARTZ, CRATON, KIMBERLITE, RIFT, METEORITE, and two lines of project RUBY. The data from RUBY also include recordings of two Kazakhstan nuclear tests. This grid of reversed profiles (also with fan recoding for RUBY) covers the East European Platform, the Ural Mountains, the West Siberian Platform and the Siberian craton, and the Baikal Rift. Dense, 3-component, short-period recordings along these profiles provide practically the only reliable source of seismic information for seismic calibration of these vast aseismic regions. These recordings offer unique opportunities to study propagation effects of regional seismic phases, to examine their correlation with geologic and tectonic features, and to develop new constraints on the structure of the crust and upper mantle. We are delivering databases of travel-time, spectral, and amplitude attributes of P, S, and Lg phases from PNE recordings. Dense observations of these phases at about 10- to 20-km spacings allow unusual, nearly continuous representation of the variations of their spectral properties over about 0- to 3200-km propagation ranges. Our preliminary analysis has uncovered numerous indications of strong Lg and other regional phases variability within the region. In order to increase robustness and versatility of the database, we provide spectral data in several forms, including the traditional (Fast Fourier Transform), multi- taper, and multi-component spectra. We summarize our recent findings from the analysis of PNE arrivals in Northern Eurasia. These results include (1) unusually detailed velocity and attenuation structure of the crust and uppermost mantle, (2) characterization of crustal attenuation through coda measurements, (3) constraints on seismic scattering, and (4) detailed imaging of the crustal basement using receiver.