ANALYSIS OF HYPOCENTER LOCATION CAPABILITY OF A REGIONAL SEISMIC NETWORK

A general procedure has been developed for analyzing the hypocenter location capability of a regional seismic network. In this analysis the fact is considered that as the earthquake magnitudes and locations vary within the region, the arrival times of P and S phases are measured by different subnets of stations.As an example, the Beijing Telemetered Seismic Network has 19 stations covering an area of about 300 km x 400 km; empirical formulae are established for determining the measurement capability of each station as a function of earthquake magnitude and instrument magnification. Then, for any possible event with a given magnitude and location, a specific geometrical configuration of a subnetwork can be determined. Based on the subnetwork configurations, the resulting distributions of errors in the hypocenter coordinates and the condition numbers of the linearized condition equation systems are estimated by the singular value decomposition technique. For various assumed earthquake magnitudes, say, 1.0, 2.0, and 3.0, the results are plotted in the form of a contour map with respect to an assumed standard error of the arrival time data.For comparison, a planned enlarged Beijing network with 61 stations is also analyzed, giving a preview of the location capability of the future network.