INITIATION OF TECTONIC EARTHQUAKES BY SURFACE MINING
G. G. Kocharyan, S. B. Kishkina
Institute of Geosphere Dynamics, Russian Academy of Sciences, Moscow, 119334 Russia
Keywords: Индуцированная сейсмичность, техногенные землетрясения, открытые горные работы, карьер, мониторинг, зона нуклеации землетрясения, разломная зона, кулоновское напряжение, Induced seismicity, triggered earthquakes, surface mining, open pit mine, monitoring, earthquake nucleation zone, faulting zone, Coulomb stress
Abstract
The influence of surface mining on the initiation of large seismic event is considered. The conditions of shearing-type dynamic events are described. In terms of a surface mine with the similar parameters as the Bachatsky open pit mine in Kuzbass, the mining-induced change in the stress state in the plane of a future rupture as a result of a triggered-type tectonic earthquake nearby a fault plant is quantified. The calculations are performed for different geometrical parameters of the fault zone: the changes are more observable in the zones of gently dipping thrust faulting and less appreciable in the area of steep normal faulting and strike-slip. In case of large surface mines, the zone of positive change in the Coulomb stresses higher than several tenths mega pascals has a considerable dimension and an area markedly larger than the area of nucleation zone of earthquakes of the magnitude . In such conditions, even a small variability at the level of first percentage points of the natural stresses can be sufficient for the initiation of seismicity-generating shearing along the high-stress faults. It is found that, as against underground mining, the surface mining activities have no influence on localization of large earthquake sources but can draw the event nearer.
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