Multifractal analysis of spatial distribution of area rockbursts at Kolar Gold Mines
The problem of mine-induced seismic events (rockbursts) has been a common feature in the century-old mines of Kolar Gold Fields (KGF) located in the southern part of India. This problem has been critical at greater depths, particularly when the ore body to be mined was associated with faults, dykes and pegrnatities. Often a major rockburst with a local magnitude of around three triggers a series of bursts numbering 20-200 of minor to medium intensity. They occur in close succession in time in the form of clusters in the region of mining activity and/or in the abandoned areas of mining (old workings). This phenomenon is termed an "area rockburst". The area rockburst is considered as an unique feature of Kolar gold mines [1-4]. The hypocenters of an area rockburst are generally spread over a larger region. Many a time area rockbursts have caused fatalities and extensive damage to the surface and underground mine structures. The area rockburst is generally influenced directly by tectonic stresses, geological discontinuities and indirectly by mining activities. Though many efforts have been made by several researchers [3-5] to understand the causes and to predict the occurrence of these area rockbursts, the success achieved has been limited. This is partly due to the complex nature of the rock mass and the complex physical process of rockbursts.