Hideaki Hase

Electric field polarization around Ioannina VAN station, Greece, inferred from a resistivity mapping

Abstract In the summer of 1997, we made a bipole–dipole mapping survey around Ioannina station of VAN (Varotsos, Alexopoulos, and Nomicos), where detection of the pre-seismic electric signal (SES) has been repeatedly reported. Since we had found the characteristic directional properties of the electric field in the previous study, the present study was aimed to examine it by investigating the shallow electric structure around the station. The apparent resistivity tensor was derived from two sets of measured voltages at each receiver position. From a rough sketch of the resistivity tensor distribution, we found that the electric field was enhanced along the direction parallel to the trend of the basin at receivers located in the conductive basin, and perpendicular to it at receivers in the resistive mountainside. Conductance distribution models with thin plates were constructed by using the measured voltages. The results showed that the VAN station is located on the resistive portion near the contact between the conductive and the resistive part. Furthermore, we simulated the apparent resistivity tensor near the VAN station on the inferred conductance distribution model. Although the directional property similar to those of magnetotelluric (MT) and lightning electric field was not reproduced there, we found that the electric field polarization is affected by heterogeneous structure not only around receivers but also around the source.

Three‐dimensional resistivity structure in Ishikari Lowland, Hokkaido, northeastern Japan—Implications to strain concentration mechanism

Rights Copyright 2017 American Geophysical Union. Yamaya, Y., T. Mogi, R. Honda, H. Hase, T. Hashimoto, and M. Uyeshima (2017), Three-dimensional resistivity structure in Ishikari Lowland, Hokkaido, northeastern Japan̶Implications to strain concentration mechanism, Geochem. Geophys. Geosyst., 18, 735‒754, doi:10.1002/2016GC006771. To view the published open abstract, go to http://dx.doi.org and enter the DOI. Type article