15 - The Role of Geological Discontinuities and Tectonic Stresses in Mine Seismicity

Abstract

This chapter discusses the role of geological discontinuities and tectonic stresses in mine seismicity. An a priori knowledge of the characteristics of pre-existing zones of weakness and the in situ stress field can aid in the identification of areas where large mining-induced events can occur. The chapter focuses on rockbursts and other forms of mine seismicity, which involve the stress-induced fracture or faulting of the rockmass. Mine seismicity is essentially rock failure because of the alteration of the virgin state of stress by mining an opening in a rockmass. Several mining factors including the depth of mining, mine geometry, and the rate and volume extracted can influence the redistribution of in situ stresses and, hence, the occurrence of rockbursts and mine seismicity. Equally important are geological factors such as surface topography, the rock properties, geological structure, and the in situ state of stress. Microseismic data, consisting of ground motion recordings of the seismic event, provide the basis for determining the event origin time, location, magnitude, source parameters such as the stress drop and source dimensions, and possibly the faulting style and orientation of the shear failure plane and the orientation and relative magnitudes of the stresses associated with the generation of the event.