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Traditionally common methods of seismic hazard assessment take into account only natural earthquakes. As result the main efforts of scientists in problem of seismic zoning are aimed to zoning factors and conditions that raise the probability of strong tectonic earthquakes. Such approach is obviously correct if the natural seismicity is dominant. Bu...
Citations
... Up to 4 m thick tabular ore body is deposited at a depth of 225-550 m stretching from NE to SW for 6 km dipping at 0-15°. The tectonic rock burst in 1990 was one of the strongest ones that ever occurred in the practice of developing Russian ore deposits [5,24,25]. Pillars collapsed and mine infrastructure was destroyed on an area of about 45 hectares, the total size of this area reached 1.2 km along the strike of the ore deposit. Seismic energy is estimated at 10 10 -10 11 J. Cracks appeared on the surface, and new traces of displacements were recorded during the survey of fault planes in the focal zone. ...
Abstract
A hypothetical mechanism of one of the strongest rock bursts ever at Russian mines is considered in this paper. Kurgazakskaya mine is located in one of the geodynamically active areas of the southern Urals near the Ay river course. The mine field is intersected by major tectonic faults, which incidentally constitute boundaries of the crustal blocks that are active in the current stress field with a horizontally oriented axis of maximum compression. Mining operations created large gob areas supported by pillars. Over and over again karst voids used to be developed at the same place of the Ay river bed where it crosses the boundary of the active crustal blocks and it is there that river water ingressed into the mine workings through tectonic faults. This paper considers the case when the normal stresses at the major fault plane decreased due to hydrostatic expansion pressure after yet another inrush of river waters into tectonic faults which triggered a tectonic rock burst with sudden fault wall displacement towards the mined-out area. It is concluded that the inrush of the Ay river water into the mine workings through tectonic faults could be the trigger of the tectonic rock burst.
Keywords
Rock burst Water inrush Fault reactivation Trigger effect
Abstract: The work is devoted to the development of issues of ensuring geodynamic safety in one of the densely populated regions of the Russian Federation, where large-scale projects for the development of subsoil are being implemented. In addition to the development of urban infrastructure, work is underway here on the construction of the Kaliningrad deposit and the mine at the Nivenskoye deposit of potassium and magnesium salts. Leads to the conclusion about the possible impact of such objects on the environment and geodynamic security of the region. The paper proposes a block diagram of geodynamic monitoring, within the framework of which studies are carried out on two objects and the territory of the city of Kaliningrad. It is also proposed to create a system of unified geodynamic monitoring, including seismological studies.
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.
