Geomagnetism and earthquake prediction

Abstract

A survey of existing data relevant to seismomagnetic effect leads to a conclusion that most of the classical reports are not free from contamination by errors, but according to recent study, a 5–15 γ change in the geomagnetic field may well be expected to accompany an earthquake of moderate magnitude. Examples of geomagnetic changes as observed by arrays of proton precession magnetometers and rubidium magnetometers are briefly outlined. It is emphasized that the most important point for this kind of observation is the elimination of non-local changes. Repetition of precise magnetic surveys also brings out local anomalous change which seems closely related to the occurrence of earthquakes. In view of recent improvement of measuring techniques, the writer is of the opinion that it is not utterly hopeless to detect a geomagnetic change as one of the forerunning effects of earthquake occurrences.