Automatic identification model of micro-earthquakes and blasting events in Laohutai coal mine based on the measurement of source parameter difference

Abstract

The micro-seismic signal of coal mine is obviously affected by blasting signal, which seriously affects the identification accuracy of micro-seismic signal. For this purpose, automated identification and discrimination methods exist to monitor seismicity occurrence. In this study, seismic source properties of blasting events and micro-earthquakes in the Laohutai coal mine are quantified to more accurately distinguish between these two types of events and to investigate potential physical differences between them. Besides examining the space–time evolution of micro-earthquakes in the Laohutai coal mine, source parameters of blasting events and micro-earthquakes (corner frequency f0; spectral level Ω0; seismic moment M0; moment magnitude Mw; source radius R; stress drop △σ; apparent stress σa, radiated seismic energy E) are determined and scaling relationships between them are investigated. Our results show that the number of micro-earthquakes is closely related to the mining activity. Source-spectral characteristics of blasting events are well described by the Brune omega-square model and follow in general the classical scaling relations (i.e. increasing seismic moment with decreasing corner frequency), like the source-spectral characteristics of micro-earthquakes. Importantly, for events of same magnitude, corner frequency and stress drop of blasting events are larger than for micro-earthquakes. This observation helps to improve automatic identification and discrimination of micro-seismic and blast events, thereby providing important information for (real-time) seismic hazard monitoring and risk management.