Accession Number:

ADA058662

Title:

Optimum Station Distribution and Determination of Hypocenters for Small Seismographic Networks.

Descriptive Note:

Final rept.,

Corporate Author:

CALIFORNIA UNIV BERKELEY SEISMOGRAPHIC STATION

Report Date:

1978-08-01

Pagination or Media Count:

48.0

Abstract:

Design of an optimal network of seismographs around a large reservoir to locate nearby earthquakes presents a number of theoretical and practical problems. This study discusses the aims of such networks and sets out general guidelines for network design to achieve these aims. The underlying variational problem is how to minimize and distribute the number of stations in order to achieve a desired level of precision in earthquake detection and hypocentral location. It is shown that a joint location method provides optimal solutions for clusters of earthquake hypocenters within a local network. A special FORTRAN program, called GHYP1 available from the Seismographic Station, University of California, has been written to do this joint reduction with simultaneous estimation of station adjustment terms. Sensitivity analyses for representative crustal models and network patterns provide guidelines for achievable hypocentral uncertainties. The problem of location of reservoir-associated seismicity is part of a more general inverse problem in which properties of the matrices of condition provide not only the variances and covariances of the estimates, but also indicate the sensitivity of the solution to changes in azimuths and distances of stations relative to the earthquake cluster. Two specific cases of earthquake sequences located near reservoirs in California are analyzed in detail using GHYP1 Oroville 1975 and Briones Hills 1977. A full explanation is given of the input and output expected for this joint location method.

Subject Categories:

  • Seismology

Distribution Statement:

APPROVED FOR PUBLIC RELEASE