ANOMALOUS EFFECTS IN THE EARTH’S ELECTRIC FIELD DUE TO STRONG EARTHQUAKES IN CASE OF KARYMSHINA SETTLEMENT, KAMCHATKA

The dynamics of the lithosphere conductivity was studied using data from monitoring impedance at a range
from the first hundreds to the first thousands of seconds. Lateral impedance and its phase were selected as basic
because they are tensor-sensitive. Behavior of impedance and its phase at periods from 460 to 1570 s revealed
abnormal magnetic bay variations that might be related to earthquakes. The appearance of the anomalies in
the impedance phase is the evidence of changes in deep layers of the lithosphere. Magnetotelluric data (MTS)
showed that the periods of these variations coincide with the conductive zone in the lithosphere associated
with a deep transverse fault. Estimates showed that lengths of the electromagnetic waves within these periods
are not less than 200 km. These lengths are enough to monitor electric conductivity of the deep conductive
zone. It is supposed that due to the earthquakes, saturation of rocks with mineralized solutions has changed.
This was most noticeable from the behavior of impedance phase. Low-frequency variations of geoelectric field
provided time series for average hourly values of potentials difference. Variations in electric field of intracrustal
sources were determined by mathematic filtration. Variations with the period of 50 hours were excluded from
the average hourly values of the electric field intensity. In addition, annual variations were also filtered out.
The received time series displayed variations in the electric field of the intracrustal sources. They were observed
on the main and redundant detector lines. The intensity of anomalies comprised up to the first hundreds of
mV/km. The aggregate signal was calculated using time series of the electric field intensity. Its behavior showed
well-defined magnetic bays. The analysis revealed that these perturbations coincided with the strong 6.4-8.3
magnitude earthquakes that struck southern Kamchatka and the Kuril Islands. We suggest that the anomalies
in the Earth’s electric field may be controlled by electrochemical, electrokinetic and other processes caused by
changes of the tectonic stress in the lithosphere due to the earthquakes.