Abstract: To characterize the stochastic features of microseismic activities in coal mining, three statistical variables, including distribution rate of microseismic energy, occurrence rate of microseismic events, and spatial distribution of events, were proposed in this paper. In addition, the methods to analyze probabilities of these variables were also established based on the  probability theory and mathematical statistical principle. The calculation results of the field microseismic data in one mine show thatthe probability density of microseismic energy presents the normal distribution;, the probability density of microseismic occurrence is similar to Poso distribution, while the probability density of microseismic spatial distribution presents multi-patterns. Meanwhile, although no certain patter is revealed from the spatial distribution, most microseismic events are occurred in the front and two sides of the working face, as well as the top and bottom of the coal seam, which means the occurrence probability of microseismic events is higher in the mutation location of rock mass characteristics. The field application proves that these three statistical variables and the corresponding probability density distributions can be well used to characterize the microseismic activities in time, spatial and energy, which may significantly improve the fundamental research in microseismic monitoring and its application in coal mining.

Key words: microseismic, activity, probability density, characteristic analysis