Physical properties of the variations of the electric field of the earth preceding earthquakes, I

The electric field variations of the earth that occur before earthquakes have been studied in a network of eighteen stations in Greece. These precursor seismic electric signals (SES) occur 6–115 h before the earthquake (EQ) and have a duration of 1 min to 112 h. The duration and the lead-time in contrast to other precursors, do not depend on EQ-magnitude (M). These signals appear as a transient change of the potential difference measured between...