An attempt to delineate very low frequency electromagnetic signals associated with earthquakes

We report on our observation of pulse-like electromagnetic signals in the frequency range 1 similar to 10 kHz that we associate with earthquakes. The severest difficulty in separating earthquake-associated VLF signals from those originating in lightning discharges steins from the circumstance that the latter signals are overwhelming in number compared with the former While claims have often been made of observation of electromagnetic signals in association with earthquakes, most of the claims, excepting a few, heavily rely on temporal correlation. By means of simple instrumentation and data processing software, our method by and large enables us to isolate VLF signals whose direction of arrival is well focussed at the epicenter direction. In this preliminary report we present several examples that positively demonstrate the existence of a class of VLF signals having a peak frequency of occurrence 1 similar to4 days prior to earthquakes of Magnitude 4 similar to6. With an accumulation of experience the technique described in this pager would seem to offer a promising approach towards earthquake prediction.