Effect of temperature on the physical precursors of rock block failure

The influence of temperature (25–400 °C) on the variations of mechanical, acoustic, electric and electromagnetic precursors of rock failure has been shown experimentally. The most significant variations were detected in the principal parameters of the acoustic and electromagnetic emissions whose impulse energy underwent a fast growth. However, the general character of hierarchical evolution stages of micro and macrofailure was practically unchanged. This has been confirmed by the so-called concentration parameter of rupture, which is theoretically calculated and checked in experiments; its space-time variations preceding the occurrence and progression of macrofailure are slightly depending on the rock temperature effect. This has been shown through the convolution of some physical precursors in a complex parameter whose variation showed an approaching of macrofailure, which remains slightly influenced by changes in temperature. Our results are interpreted in relation to physics of superficial earthquakes and precursors.