Status report on method and results for new discriminants and combinations of discriminants for different ranges

摘要

A number of discriminants have been developed for seismic monitoring. These include the Ms-mb discriminant which measures differences in surface and body wave magnitudes (e.g., Marshall and Basham, 1972), short period P to S wave amplitude ratio discriminants (e.g., Blandford, 1981) and spectral ratios discriminants (e.g., Murphy and Bennett, 1982). Unfortunately, existing discrimination capabilities are insufficient to meet the needs that will be required by a comprehensive test ban treaty (CTBT). Of particular concern are limitations of current capabilities for discriminating small magnitude (mb<4) seismic events such as earthquakes, mining explosions, and mining related seismicity (rockbursts and collapse events) from small magnitude nuclear explosions (both coupled and decoupled). In this report, we summarize our work on the development of new methods for discriminating such small magnitude events.