Geodesy and Geodynamics (Jan 2021)
A proposed classification of the Earth's crustal areas by the level of geodynamic threat
Abstract
It is accepted as a well-known fact that in different places on the Earth's crust, a similar anthropogenic impact causes a dissimilar response. Seismic zoning maps are not designed to predict such geodynamic hazards as rock bursts, induced earthquakes, reactivation of tectonic faults, etc., and therefore require careful adjustments in places of intense impact on the subsurface strata. In this regard, we consider the classification of the Earth's crustal 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 a critically stressed layer within the Earth's crust extends from the Earth's surface to a certain depth, and 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. We recognize the hypothesis that the thicker the critical stressed rock layer, the stronger the response might be to anthropogenic intervention, as it has more accumulated energy. Four categories of geodynamic threat have been found and mapped. To verify this classification, the manifestations of the geodynamic hazards were studied. The intensity of geodynamic hazard increased from the first area to the fourth area. The phenomenon of large induced seismic events with hypocenters at great depths is explained on the basis of this theory, and could be associated with anthropogenic impacts from the surface directly on the regional zone of the critically stressed rock massif. The approach can be used to assess the geodynamic consequences of human exposure to the Earth's crust.
