On Classification of the Earth's Crust Areas by the Level of Geodynamic Threat

Abstract

It is accepted as a well-known fact that a similar anthropogenic impact on the Earth's crust in different places causes dissimilar response. Seismic zoning maps are not designed to predict such geodynamic hazards as rock bursts, induced earthquakes, reactivation of tectonic faults, etc., and require careful adjustment in places of intense impact on the subsurface strata. In this regard, we consider the classification of the Earth's crust areas according to the degree of geodynamic hazard, i.e. its potential geodynamic response to anthropogenic intervention. This classification is based on the concept that there exists a critically stressed layer within the Earth’s crust. It is believed that such critically stressed layer within the Earth’s crust extends from the Earth's surface to a certain depth, which at each point depends on the nature of the interaction between crustal blocks of different hierarchical levels.From this perspective, anthropogenic impact, such as mining operations, represents a direct impact upon the critically stressed zone. The hypothesis is accepted that the thicker is the critical stressed rock layer, the stronger might be the response to anthropogenic intervention, as it has more accumulated energy. Four categorized of the geodynamic threat were found and mapped. To verify this classification, the manifestations of the geodynamic hazards were studied. The intensity of geodynamic hazard increases from the 1st area to the 4th area. The phenomenon of large induced seismic events with hypocenters at great depths is explained by the base of this idea and could be associated with anthropogenic impacts from the surface directly on the regional zone of the critical stressed rock massif. The approach can be used to assess the geodynamic consequences of human exposure to the Earth's crust.