Research at the Center for Seismic Studies. Part 2

Abstract : This is Part 2 of a two part report. It contains papers primarily focused on regional monitoring of underground nuclear explosions. A broad spectrum of issues is addressed from improving automatic processing to an assessment of monitoring capability using certain network configurations. The first two papers examine the use of three-component seismic data for phase identification; one applied discriminant analysis to the three-component IRIS/IDA stations in the former USSR in anticipation of those stations being added to the Intelligent Monitoring System (IMS), and the other applied the same techniques to the three component stations of ARCESS and NORESS in a comparison with newly-developed neural network techniques. The third section used travel- time information from long range refraction profiles that is independent of the IMS to derive an average travel-time curve for Fennoscandia. In addition, regional variations in the Pn travel times are defined and used to relocate a small set of events. The fourth paper is the result of work performed on a Deep Seismic Sounding profile that was obtained by the USGS. The validity of the preliminary interpretation of the data by Russian seismologists is examined in this paper. The final two sections deal with monitoring networks. One presents the results of network simulation of the GSE Network using empirical noise calculations from the recent technical test. The other is a summary note on starting and improving a regional network. It summarizes and integrates the results of our research related to the way the US would proceed to monitor with an in-country regional network of three-component (3-C) stations and arrays.