Occurring Conditions of Atmospheric Electricity Variation during Seismic Wave Propagation

We have observed the co-seismic electromagnetic phenomena such as earth potential difference (EPD) variation and atmospheric electricity (AE) variation at three observation sites in Akita Prefecture. In the strong earthquake of December 2nd, 2001, we observed clear signals of the EPD and the AE variation at all three sites. However, the amplitude of both observed signals at three sites are very different though with almost equal quake intensity at each site. The AE signal amplitude is increasing with the EPD signal one at each site. The model how both variation signals appear is proposed to explain the observed data.