Regional Characterization of Mine Blasts, Earthquakes, Mine Tremors, and NuclearExplosions using the Intelligent Seismic Event Identification System

摘要

This report describes the results of a study of the Intelligent Seismic EventIdentification System (ISEIS) which was installed at the Center for Seismic Studies and applied to regional events in the Intelligent Monitoring System (IMS) database. A subset of IMS data has been collected for known events in a database called the Ground Truth Database (GTD) and these events were processed by ISEIS. This has shown that the regional high-frequency PIS ratio discriminates between explosions and earthquakes in the Vogtland region recorded at the GERESSS array. Mine tremors in the Lubin and Upper Silesia resemble earthquakes. Lg spectral ratio was found to separate explosions and earthquakes in the Vogtland region, but the Lubin and Upper Silesia region mine tremors had large scatter. An evaluation was made of the discrimination rules in the ISEIS expert system on the events in four regions (Vogtland. Lubin, Upper Silesia, and Steigen) in the GTD. This report also describes the results of the analysis of the December 31, 1992 event which occurred near the Russian test site on Novaya Zemlya. Analysis of Pn/Sn ratios at NORESS indicated that these ratios were comparable to those measured for Kola Peninsula mine blasts, although the propagation paths were different. The ratios were only slightly greater than those observed for earthquakes in the Greenland Sea. The August 1. 1986 event recorded was re-analyzed and also found to resemble mine blasts. However, other discriminants indicate that the event was probably an earthquake.