Evaluation of Seismometer Arrays for Earthquake Location

Abstract

Program HYPOERR evaluates the performance of a small network of arbitrary seismic arrays in determining coordinates and times of seismic events. A linearized inversion following the method of Uhrhammer (1980)is performed for a layered velocity structure by determining the eigenvalues and eigenvectors of the partial derivatives of travel time for P and/or S phases with respect to hypocenter position and origin time for each station in the array. A series of covariance matrices is then obtained to evaluate statistical errors for a specified grid of hypocenter locations at any given depth. Contour plots can then be made of the matrix elements by using standard contouring software. Examples are given for ( 1) the case of a hypothetical quadrapartite array and (2) an actual eight-station ocean-bottom seismometer array deployed around the 95.5° W. Galapagos propagating-rift zone.