Use of a high speed computer for the preliminary determination of earthquake hypocenters

Abstract

At the U. S. Coast and Geodetic Survey, where preliminary earthquake locations must be computed from as many as 30,000 initially unrelated P arrivals and associated phases per month, considerable effort has been devoted toward making this process more fully automatic. A single pass program, COAST, has now been developed for use on the IBM 7030 (STRETCH) computer. This program discriminates compatible time groups from an uncorrelated chronological data file, computes a first approximation to the hypocenter using only five stations, and determines the refined hypocenter and earthquake magnitude using all relevant data without any intervention by a seismologist.