The effect of crossed electric and magnetic fields in loaded rock specimens

The idea of the work is to demonstrate that impacts of crossed electric and magnetic fields (Cr.EMF) are applicable to study the rate of internal fracturing processes in loaded rock specimens. Our previous experiments with rock specimens loaded by a press have revealed the effect of acoustic emission (AE) activity increment caused by electric pulses. The experiments have been held on a noiseless rheological machine available at Bishkek Geodynamic Research Center—RS RAS. We analyzed the temporal dependence of AE activity during exposure to crossed electric and magnetic field; the compressive load being constant. The effect of AE stimulation by power pulses (triggering) has been verified. AE measurements have confirmed the existence of explicit response to both kinds of Cr.EMF pulses: solitary pulses with major amplitudes of E and B and periodic long-term pulses of minor E and H amplitudes. The comparison of recent and previous results on AE triggering by external electromagnetic (EM) fields has demonstrated that two modes of activation can be distinguished. Both kinds of AE variations (responses) are manifestations of change in internal friction (microcracking and kinetics of other defects).