Technical Report for the Period 1 January-31 March 1987,
SCIENCE APPLICATIONS INTERNATIONAL CORP ARLINGTON VA CENTER FOR SEISMIC STUDIES
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Results of the assessment of capabilities of seismic networks and the design of networks show that a networks location accuracy approaches a near-maximum when stations are distributed over an azimuthal sector of about 180 deg and that good depth determination requires stations within about 15 deg of the focus of the event. The latter suggests that global networks should include 100 or more seismological stations if accurate depth estimation is important. A study of about 100 local and regional events detected by NORESS is a systematic effort to test analytical methods being developed for extracting features from seismic waveforms that can be used to identify regional phases, and for recognizing repeated events from a single source such as quarry blasts. The methods under evaluation includes the extraction of frequency-domain spectral parameters, and particle motion information. Substantial effort was devoted to developing concepts and preparing for experiments in international exchange of of seismic waveform data. This work included developing the technical concepts for a potential global seismic monitoring system. The Center has been heavily involved in an examination of its database management system and the development of extensions to handle new types of data-principally data from seismic arrays and data anticipated from forthcoming GSE experiments. Keywords Nuclear explosion monitoring, Seismic wave attenuation.