Publications Details

Network modeling and an evaluation of a CD proposed ISMS

Claassen, J.P.

This report briefly describes the improvements and corrections made to a seismic network performance modeling code called NetSim. After expanding its supporting database, the modified code was used to predict the detection and location performances of an International Seismic Monitoring System (ISMS) proposed early in 1995 by the Group of Scientific Experts (GSE) supporting the Comprehensive Test Ban Treaty (CTBT) negotiators. The performance estimates indicated that the primary network achieves or exceeds the GSE goal of detecting a fully coupled 1kiloton nuclear shot contained in consolidated rock anywhere on the earth. It was also shown that without calibrated regional location models, the primary network alone cannot achieve the GSE location accuracy requirement of 1000 square kilometers at the detection threshold of the primary network, but with the help of 67 auxiliary stations that goal can be achieved in the northern hemisphere. Once the regional location models become better calibrated, the predictions based on these models indicated that the primary network should be able to realize the GSE requirement throughout much of the world. However, the location accuracy requirement is not realized in Central America, on the oceanic islands, on continental margins in the southern hemisphere, and in Antarctica. The introduction of the 67 auxiliary stations into the calibrated network primarily broadens the regions already having good location accuracies. The location performance estimates may be regarded as conservative since the S-wave arrivals were not included A comprehensive set of scenarios are illustrated in this effort to better understand various influences on network performance.