- Copyright © 1965, by the Seismological Society of America
Even, inverse noise filters have been used in an automatic scheme for the detection of small arrivals. Precursors have not been created by this method. The significance level is estimated by computing the number of points in a normal noise record which have the same amplitude. The method has been successfully tested on actual earthquakes. Starting with a digitized seismogram, it automatically finds the arrivals, prints their time, their direction, and their standard deviation, and plots the spectra and the seismograms. Examples are given.