矿山地震活动多重分形特性与地震活动性预测

SEISMIC MULTI-FRACTAL CHARACTERISTICS IN MINES AND SEISMICITY PREDICTION

矿山地震活动可直接揭示矿山岩体活动状态和危险性水平。利用冬瓜山铜矿矿山地震监测数据,采用广义关联积分计算地震震源空间分布的分形维,利用Gutenberg-Richter关系中的b值与地震事件能量分形维关系计算地震能量分形维,并结合开采活动及矿山结构特征,研究矿山地震活动的分形结构特性和时域谱特征。研究结果表明,矿山地震活动具有多重分形特性,它与开采活动及矿山结构特点之间存在相关性;只有当计算空间区域的地震分形结构较均匀时,其分形维才能有效应用于地震活动性预测。这些空间通常对应于采掘类型少和结构单一的空间区域。地震空间分布分形维D∞反映了矿山地震活动状态,其时域谱具有较好的主震前兆特征,可以作为地震预测的参数;D2-D∞时域谱的地震前兆性较差,较难预测主震。

The characteristics of the fractal of seismicity in mines play an important role in the establishment of a nonlinear dynamics of seismicity in mines for prediction of seismicity.With seismic data detected in Dongguashan Copper mine,the fractal dimensions of spatial distributions of seismic hypocenters were calculated in the generalized correlation integral,and the fractal dimensions of energy of seismic events were calculated in the relation between b-values in the Gutenberg-Richter law.The fractal structures of seismicity in the mine and their temporal spectra were researched by means of multi-fractal theory,combining with the mining activities and mining engineering structures.The results show that seismicity in the mine has multi-fractal,and the heterogeneity of fractal structure of seismicity is of mining activity and engineering structure.Only if the fractal structure of seismicity in a space for fractal calculation is relative homogeneous,its fractal dimensions can be adopted to effectively predict seismicity.This space for the fractal calculation generally has few sorts of mining activities and simplex engineering structure,and the fractal dimensions of spatial distribution of seismic epicenters reflect the state of the induced seismicity.The temporal spectrum D∞ has an obvious precursor of main shock and is suitable for seismicity prediction,but the D2-D∞ has no obvious precursor of main shock and is not suitable for seismicity prediction.