A possible explanation for detecting seismic electric signals at certain sites of the Earth's surface

A plausible model is suggested, which explains that weak currents, emitted (before an earthquake) from the focal area, are sufficient to produce detec table seismic electric signals at epicentral distances r approximate to 100 km. It is found that these precursor signals can be detected at particular sites on the Earth's surface, thus explaining the so-called selectivity ef fect.