Accession Number : ADA302362

Title :   Case Studies of Seismic Discrimination Problems and Regional Discriminant Transportability.

Descriptive Note : Final rept. 25 Jun 93-24 Jun 95,

Corporate Author : ENSCO INC SPRINGFIELD VA SIGNAL ANALYSIS SYSTEMS DIV

Personal Author(s) : Baumgardt, Douglas R.

PDF Url : ADA302362

Report Date : 31 JUL 1995

Pagination or Media Count : 87

Abstract : This report describes case studies of regional seismic discriminants, using the Intelligent Seismic Event Identification System (ISEIS), and addresses issues related to the transportability of regional discriminants. Some of the key results of this study include: (1) Observations of large Lg waves from mine blasts. (2) Investigation of the P/S frequency-dependence discriminant. (3)The importance of signal decorrelation in the generation of spectral scalloping by ripple fired mine blasts. (4) Path corrections for the Lg spectral ratio discriminant using a simple anelastic attenuation model. Also described in this report is a discrimination study of the January 5, 1995 Urals mine event. Because there were no nearby earthquakes or blasts in the Urals mine region, recordings of the event at regional station ARU were compared with WMQ recordings of Chinese nuclear blasts and earthquakes at comparable distance, but in a different geographic and tectonic region. This comparison indicated that the January 3, 1995 event had Pn/Lg amplitude ratios more comparable to Chinese earthquakes than nuclear explosions. Based on the analysis of Pn/Lg ratios at NORESS and comparison those produced by PNEs in the same region recorded at NORSAR, we conclude that the January 3, 1995 event produced much stronger shear waves (Sn, Lg) relative to P than did nuclear blasts. We conclude that the event was probably a mine tremor or collapse.

Descriptors :   *UNDERGROUND EXPLOSIONS, *SEISMIC DISCRIMINATION, RATIOS, ELASTIC PROPERTIES, CASE STUDIES, IDENTIFICATION SYSTEMS, RIPPLES, ATTENUATION, NUCLEAR EXPLOSION DETECTION, EARTHQUAKES, CORRELATION TECHNIQUES, AMPLITUDE, SEISMOLOGY, DISCRIMINATE ANALYSIS, CORRECTIONS, SEISMIC ARRAYS, TECTONICS, MINES(ORDNANCE), MINES(EXCAVATIONS), TREMORS.

Subject Categories : Seismic Detection and Detectors

Distribution Statement : APPROVED FOR PUBLIC RELEASE