Accession Number : ADA306407

Title :   Design, Evaluation, and Construction of TEXESS and LUXESS and Research in Mini-Array Technology and Use of Data From Single Stations and Sparse Networks: Phase 5.

Descriptive Note : Scientific rept. no. 5,

Corporate Author : SOUTHERN METHODIST UNIV DALLAS TX

Personal Author(s) : Herrin, Eugene ; Golden, Paul ; Robertson, Herbert

PDF Url : ADA306407

Report Date : OCT 1995

Pagination or Media Count : 97

Abstract : In a descrimination study corollary to the AR method, phase matched filtering techniques were used to analyze Rg dispersion from mine blasts. Short period surface waves from chemical explosions were used to obtain reliable dispersion curves for surface waves being generated, and to establish any azimuthal variations in relative Rg (fundamental-mode, short-period Rayleigh wave) energy at azimuths around the quarry, including the quarry pit's influence on these energy variations. Observed dispersion curves were interpreted using theoretical dispersion curves that consider estimated values of Poisson's ratio (0.35-0.4) for the central Texas' upper crust. The Rg dispersion has 3 sections; an inversely dispersed branch complicated by the presence of higher modes (at periods less than 0.6 seconds), a group velocity minima (at periods between 0.6 and 0.7 seconds), and normally dispersed Rg (between 0.7 and 3.0 seconds with an inflection point near 1.7 seconds). In the period interval between 0.7 and 1.5 seconds, multipathing complicates interpretation of the dispersion curve by creating spectral holes in multiple filter analysis (MFA), a single station routine for calculating group velocity dispersion. Spectral holes must be dealt with before interpreting the final dispersion curve, which is then used to extract Rg from the complex wave train by phase match filtering (PMF). Rg extracted from paths not traversing the open pit of the quarry have more energy than paths influenced by the open pit. Likewise, higher mode energy exceeds fundamental mode energy only when the propagation path includes the open pit.

Descriptors :   *UNDERGROUND EXPLOSIONS, *NUCLEAR EXPLOSION DETECTION, *SEISMIC DISCRIMINATION, SURFACE WAVES, DISPERSING, GRAPHS, GROUP VELOCITY, HOLES(OPENINGS), MATCHED FILTERS, POISSON RATIO, RAYLEIGH WAVES, MINES(ORDNANCE).

Subject Categories : Seismic Detection and Detectors

Distribution Statement : APPROVED FOR PUBLIC RELEASE