Rock Destruction and Metamorphic Processes in the Earth: A Look from Classical Physics

Investigation of mountainous rock destruction and metamorphic processes under different thermodynamic conditions is one of the most important problems of global and engineering geophysics. Solving the mentioned problems is impossible without the careful studying of mountainous rock stability. It was considered earlier that destruction of some material is taking place when at least one component of the stress tensor reaches some critical value called “material durability”. However, conducted analysis allowed us to conclude that such a notion is correct only for relatively short-term action and is unsuitable for the prolonged stress to target. Instead of the notion “durability”, we suggest using the notion “longevity”. On the basis of detailed theoretical analysis, we propose a new physical-mathematical conception describing the destruction process as a phase transition. From this viewpoint, the generation of microfault (occurrence of empty space with maximal stress concentration) is an initiation of a new phase. The development of such a new conception permits to recognize new relations between the destruction process on the one hand and time, the strength, temperature, pressure, and characteristics of the crystal lattice of mountainous rock on the other hand. It was determined that the microfault generation causes the emission of a definite number of seismo-acoustical impulses. The quantity of the impulses during the time unit determines the intensity of the process destruction and the frequency of oscillation indicates the dimension of the microfaults forming. We propose that a global changing of geological rocks under the effect of different physical factors (metamorphism) may be also analyzed using the common approach considering the process as a phase transition. Therefore, some conclusions obtained for the rock destruction analysis may be transferred to metamorphic processes. The suggested conception makes possible procedures for forecasting dangerous seismological events as well as for longevity monitoring of different artificial underground constructions: buildings, mines, and reservoirs as well as other artificial and natural structures.