Description: To facilitate the development testing and comparison of regional seismic discriminants, we have implemented some of the most promising techniques in Matseis, a-Matlab-based seismic processing toolkit. The existing Matseis package provides graphical tools for analyzing seismic data from a network of stations. It can access data via a CSS 3.0 database, or from static files in a format defined by the user. Waveforms are displayed in a record-section format, with overlays for IASPE191 travel-time curves. The user can pick arrivals and locate events, then show the results on a map. Tools are available for spectral and polarization measurements, as well as beam forming and f-k analysis with array data. Additionally, one has full access to the Matlab environment and any functions available there, as well as to portions of the U.S. Department of Energy Knowledge Base. Recently, we have added some new tools to Matseis for calculating regional discrimination measurements. The first of these performs Lg coda analysis as developed by Mayeda and coworkers at Lawrence Livermore National Laboratory (LLNL). Lg coda magnitudes are calculated from the amplitudes of the coda envelopes in narrow frequency bands. Ratios of these amplitudes between high- and low-frequency bands provide a spectral-ratio discriminant for regional events. The second tool we have implemented measures P/Lg phase ratios, using the MDAC technique of Taylor (Los Alamos National Laboratory) and Walter (LLNL). P and Lg amplitudes are obtained at select frequencies, then corrected for source magnitude and propagation path. Finally, we added a tool for analyzing long-period Rayleigh and Love arrivals, useful for moment:magnitude and LQ:LR discrimination. Because all these tools have been written as Matlab functions, they can be easily modified to experiment with different processing details. The performance of the discriminants can be evaluated using any event available in the database.
Date: August 3, 1999
Creator: Chael, Eric; Harris, Mark; Young, Chris; Mayeda, Kevin; Walter, William; Taylor, Steve et al.
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