Explosions at large distances from the Berkeley seismic array of the University of California have been studied in an attempt to obtain an estimate of a P travel time “adjustment” function for each station in the array relative to a standard P table. The probability distribution of residuals is discussed and some error estimates for station adjustments given.
A method is suggested for relocating groups of events occurring in small regions. This problem was suggested by the existence of groups of explosions in small regions which gave rise to widely varying sets of residuals.
The probable presence of azimuthally varying source, as well as station, terms makes it advisable to obtain times from world-wide stations for each source area in order to attempt to separate the two terms. In fact, the presence of these terms makes it questionable whether a meaningful adjustment function for a single station can be obtained at all.