LLNL's Regional Model Calibration and Body-Wave Discrimination Research in the Former Soviet Union Using Peaceful Nuclear Explosions (PNEs)
Abstract
Long-range seismic profiles from Peaceful Nuclear Explosions (PNE) in the Former Soviet Union (FSU) provide a unique data set to investigate several important issues in regional Comprehensive Nuclear-Test-Ban Treaty (CTBT) monitoring. The recording station spacing (approx. 15 km) allows for extremely dense sampling of the propagation from the source to greater than or equal to 3300 km. This allows us to analyze the waveforms at local, near- and far-regional and teleseismic distances. These data are used to: (1) study the evolution of regional phases and phase amplitude ratios along the profile; (2) infer one-dimensional velocity structure along the profile; and (3) evaluate the spatial correlation of regional and teleseismic travel times and regional phase amplitude ratios. We analyzed waveform data from four PNE's (m(b) = 5.1 - 5.6) recorded along profile KRATON, which is an east-west trending profile located in northern Siberia. Short-period regional discriminants, such as P/S amplitude ratios, will be essential for seismic monitoring of the Comprehensive Nuclear-Test-Ban Treaty (CTBT) at small magnitudes (m(b)<4.0). However, P/S amplitude ratios in the short-period band, 0.5 - 5.0 Hz, show some scatter. This scatter is primarily due to propagation and site effects, which arise from variability in the elastic and anelastic structure of the crustal waveguide. Preliminary results show that Pg and Lg propagate efficiently in north Siberia at regional distances. The amplitude ratios show some variability between adjacent stations that are modeled by simple distance trends. The effect of topography, sediment and crustal thickness, and upper mantle discontinuities on these ratios, after removal of the distance trends, will be investigated.
Document Details
- Document Type
- Technical Report
- Publication Date
- Sep 01, 2000
- Accession Number
- ADA526844
Entities
People
- Arthur Rodgers
- Craig Schultz
- Geoff Clitheroe
- Jennifer Swenson
- Joydeep Bhattacharyya
- Walter Mooney
- William R. Walter
Organizations
- Lawrence Livermore National Laboratory