Remote Detection of the Electric Field Change Induced at the Seismic Wave Front from the Start of Fault Rupturing
High-speed monitoring record of electric field variation at Hasaki inducing considerably similar electric field changes starting from the origin time of the earthquake on October 16, 2002 (E2 in Figure 1), like the case shown in Figure 2. Vertical bars are the origin time, P wave arrival, and S wave arrival of the strong motion seismogram, respectively. The two cases have common features: there is an initial increase of strength of the electric field approximately coinciding with the earthquake origin time, and the largest variation after the S wave arrival lasts for several tens of seconds. In both cases there was no peak at the time of P wave arrival.