Overview of seismic monitoring and assessment of seismic hazard based on a decade of seismic events

Abstract

-During mining activity, the natural equilibrium of the rock mass gets altered resulting in increase in stress causing sudden, violent failure of rock mass. The stress increases with increase in the depth of mining. The dynamic stress changes caused due to release of strain energy from within the rock mass in the form of seismic signals are termed as seismic events. The occurrence of seismic events has been a regular phenomenon in and around the abandoned mines of Kolar Gold Fields causing damage to the surface structures and inducing apprehension about the safety and stability of mining areas. Among the abandoned mines, one of them had reached mining depth as deep as 3200m. In this sensitive mining area, there has been occurrence of many seismic events that were monitored by a dedicated seismic monitoring system from time to time. The monitoring system was used to determine the location of seismic events and used as an indicator of precaution from future events. In the background of this monitoring history, an attempt has been made here to assess the overall scenario of seismic hazard due to the seismic events observed over one decade. This study focuses on assessing the current probable seismic hazard for the abandoned mining region by using the estimated source parameters such as source radius, seismic magnitude obtained from the data of strong motion accelerometer supported by data from existing broad band seismometer.