Electromagnetic Emission Caused by the Fracturing of Piezoelectrics in Rocks

Electromagnetic emission caused by the fracturing of piezoelectrics in rocks has been studied. It is revealed that the source of the emission is the transient magnetization appearing due to the moving crack. The frequency-angle distribution of the emission is found. The maximal frequency of the emission is determined by 1/T0, where T0 is the time of the crack's movement in the material. The wavelength is about L/V (V is the velocity of the moving crack and L is the size of the piezocrystal in the rock). The polar pattern of the emission is located in the piezoactive plane of the crystal. The considered problem is very promising for investigations of natural hazards as seismic and volcano activities.