The physical basis of the effects caused by electromagnetic forcing in the intensity of geoacoustic processes

Modulation of geoacoustic emission intensity by time-varying electric field

“…Figure 1a shows a fragment of the initial geoacoustic time series which demonstrates, firstly, the changes in the root mean square (RMS) values of daily GAE variations and, secondly, the changes in the trend component of GAE data, which envelopes the GAE time series from below. To explain, we note that according to the results of numerous works (e.g., [Gavrilov et al, 2014]), the daily GAE variations for the zone of the G-1 borehole are responses to the daily variations of the external electromagnetic radiation (EMR) in the area of the G-1 borehole in the frequency band 160 ± 20 Hz ( Figure 1b).…”

“…For stages I and II, the multi-instrumental logging data have been fairly thoroughly analyzed in [Gavrilov et al, 2014;Ryabinin et al, 2011Ryabinin et al, , 2012. It was shown that the sharp and strong buildup of the amplitudes of GAE responses at stage II can be accounted for by the increase in fluid saturation within the noise zone of the geophone due to the fluid inflow from the deeper geological horizons and the enhancement of electrokinetic processes.…”

“…The results of integrated logging measurements that have been conducted during many years at the Petropavlovsk-Kamchatsky geodynamical testing area indicate clearly promising outlook for monitoring the strain-stress state of the geological medium based on the modulating effects of the external electromagnetic fields on the intensity of geoacoustic emission (GAE) [Gavrilov et al, 2014]. Understanding the probable physical mechanisms of this effect is one of the key prerequisites for correct interpretation of the results of these measurements.…”

“…Understanding the probable physical mechanisms of this effect is one of the key prerequisites for correct interpretation of the results of these measurements. In the previous works in this direction, the modulating effect of the weak ELF electromagnetic fields (a few hundred Hz) on GAE intensity was accounted for by the changes in viscous friction between the mobile part of the fluid and the surface of the solid phase [Gavrilov, 2014;2016]. In this model, a fluid was assumed to be viscoplastic and to have the shear resistance not entirely governed by viscosity but also controlled by static friction (the Bingham fluid).…”

On the mechanism of intensity variations of geoacoustic emission caused under the action of audio-frequency electromagnetic field

“…The physical factors and mechanisms responsible for the sensitivity of the intensity of geoacoustic processes to the external electromagnetic impacts of audio frequencies (a few hundred Hz) in the real medium were studied in a number of the publications [Gavrilov, 2007;Gavrilov et al, 2006Gavrilov et al, , 2013Gavrilov et al, , 2014. For the first time, this effect was identified in the results of the complex measurements in the boreholes of the Petropavlovsk-Kamchatsky geodynamical testing area, which were started in 2000.…”