Change in Fault Zone Permeability Due to Seismic Vibrations

The prediction of emergency situations arising from water breakthroughs during the development of solid mineral deposits or during the construction of large underground structures is very difficult due to the high heterogeneity of filtration properties of the rock mass and the uncertainty of hydrogeological characteristics of fault zones, which are the main pathways for fluid flow. This paper studies several mechanisms of changes in the hydraulic characteristics of fault zones under the influence of seismic vibrations. We use observational data obtained during large underground explosions in rock masses as an experimental basis. The study analyzed unique archival materials obtained at the Institute of Geosphere Dynamics of the Russian Academy of Sciences during the preparation and execution of large-scale underground explosions conducted by the USSR at the Semipalatinsk Test Site (now the Republic of Kazakhstan) and at several mining enterprises in Russia. As a result, cases of predominance of different mechanisms of permeability change have been distinguished across a wide range of dynamic loads. The analysis performed has led to the conclusion that even relatively weak dynamic impacts can cause a noticeable hydrogeological response. Moreover, this occurs not due to the formation of new filtration pathways, but due to “clearing” the already existing fracture-pore space.