【摘要】 利用遗传算法,搜索符合Brune ω2模型的拐角频率(fc)及零频幅值(Ωc)的最佳值,测定浙江珊溪水库震区88条小震(1.5≤ML≤4.6)的地震矩(M0)、震源尺度(r)及静态应力降(Δσ)。地震矩M0在1010~1014N.m范围内,与拐角频率fc遵循M0∝fc-3的规律;震源尺度和地震矩、应力降之间呈现多重标度特征,地震矩大于临界值2.3×1012N.m(相应的震源尺度特征值约160m)时,震源尺度与地震矩的关系较强;而应力降(Δσ)在震源尺度大于160m后基本趋向恒定,不随震源尺度的增大而增大。浙江珊溪水库震区自2002年7月以来,经历2次大规模的震群活动。震群释放的应力降大小与该震群的规模成正比关系,大的应力降集中在发震断层中段5~6km深度的区域,其发生时间既可以在主震之前,也可以在主震之后。更多还原

【Abstract】 The seismic moment(M0),source dimension(r),and static stress drop(Δσ)of 88 small earthquake occurred in the Shanxi-Reservoir,Zhejiang Province,were determined using genetic algorithms to searching the low-frequency flat levels(Ωc)and corner frequencies(fc)with the best-fitting Brune ω2 model.The seismic moment varied between 1010-1014 N·m,versus the corner frequency followed the scaling law M0∝ f-3c;Source dimension,versus the seismic moment and static stress drop,were multi-scaling characteristic,dependency of the source dimension on the seismic moment were stronger while seismic moment greater than 2.3×1012 N·m with the source dimension(r)equals 160 m;Stress drop tend to be invariant while source dimension greater than 160 m.Since July 2002,two greater earthquake swarms occurred in the Shanxi-Reservoir.The stress drop level depends on the magnitude of earthquake swarm.The greater stress drop concentrated in 5-6 km depth on the fault plane,after or before the main-shock.更多还原