Next-Generation MDAC Discrimination Procedure Using Multi-Dimensional Spectral Analyses

• Main Authors: Fisk, Mark D., Taylor, Steven R., Patton, Howard J., Walter, William R.
• Other Authors: NATIONAL NUCLEAR SECURITY ADMINISTRATION WASHINGTON DC
• Format: Text
• Language: English
• Published: 2007
• Subjects: Test Facilities; Equipment and Methods; Seismic Detection and Detectors; Nuclear Explosions and Devices(non-military); *NUCLEAR EXPLOSIONS; *UNDERGROUND EXPLOSIONS; *SPECTRUM ANALYSIS; *EARTHQUAKES; *SEISMIC DISCRIMINATION; *SURFACE WAVES; LONG RANGE(TIME); ALGEBRA; MODELS; SIZES(DIMENSIONS); AMPLITUDE; SYMPOSIA; *NEXT GENERATION; LOP NOR; SEMIPALATINSK; NOVAYA ZEMLYA; Brune; Mueller; Novaya Zemlya
• Online Access: http://www.dtic.mil/docs/citations/ADA519673; http://oai.dtic.mil/oai/oai?&verb=getRecord&metadataPrefix=html&identifier=ADA519673

Theoretical understanding of regional P/S discriminants and their frequency dependence has been an important, long-standing research topic. Following Xie and Patton (1999), Fisk et al. (2005) and Fisk (2006) used modified Brune (1970) and Mueller and Murphy (1971) [MM71] models to explain the frequency dependence of Pn/Lg and Pn/Sn discrimination performance for earthquakes and underground nuclear explosions (UNEs) near the Lop Nor, Semipalatinsk, and Novaya Zemlya test sites as mainly due to differences in explosion P and S corner frequencies. Fisk (2007) used source model fits to estimate Pn, Pg, and Lg corner frequencies for Nevada Test Site (NTS) explosions and found that Lg corner frequencies exhibit similar scaling with source size as for Pn and Pg, but shifted lower, analogous to observations by Fisk (2006) for other test sites. A key result is that increasing separation of regional P/S at higher frequencies between earthquakes and explosions at all of these test sites has a consistent model-based explanation mainly in terms of the difference between explosion P and S corner frequencies. Discrimination begins to improve at the explosion S-wave corner frequency and saturates at the explosion P-wave corner frequency, in agreement with empirical experience obtained over decades. We describe how grids of P/S spectral ratios for all combinations of frequencies for P and S wave spectra, which exhibit far greater differences in relative spectral amplitudes and shapes between explosions and earthquakes than considered before, and source models can be used to significantly enhance discrimination performance and confirm the physical basis of the results. Published in the Proceedings of the Monitoring Research Review: Ground-Based Nuclear Explosion Monitoring Technologies (29th) held in Denver, CO on 25-27 Sep 2007, p551-560. The original document contains color images.