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本文介绍湖南镇水库1982年5月22日M_L=3.1级地震序列的近场地声观测和初步研究结果。观测表明:每一次地震都伴随地声。地声系相应地震事件辐射的高频弹性体波。其经由地面透射与空气耦合后形成可听地声。地声活动性在3.1级主震前后呈明显的阶段性变化特征。地声频率为60—250Hz,其加速度功率谱主频率f_D为80—150Hz。研究了主频率的时间序列,发现前震期地声主频率由高值向低值转移,主震时达极低值。余震期内,主频率则由低值向高值回升,f_D与M_L呈幂函数关系f_D=130.7×(M_L+2)~(-0.3)。研究表明,地声主频率与时间、震级的相关性主要取决于震源破裂尺度,同时也与震源介质的应力状态和品质因数Q值变化有关。3.1级地震序列的近场地声观测和研究结果,与近年来国内外岩石破裂过程与声发射活动性和波谱特征的实验研究结果颇为一致。它表明,在矿山和地震活动区进行近场地声连续观测和实时分析,对岩爆和地震过程的预测有重要意义。
This paper presents the near-field acoustic observations and preliminary studies on the M_L = 3.1 earthquake sequence of Hunan Zhenjiang Reservoir on May 22, 1982. Observations show that every earthquake is accompanied by earthquakes. Earth Acoustic Corresponding earthquake event radiated high-frequency elastomeric waves. It is acoustically audible after being coupled to the air via the ground. Ground acoustic activity in the 3.1 before and after the main shock was significantly different characteristics of the stage. Ground acoustics frequency of 60-250Hz, the main frequency of the acceleration power spectrum f_D 80-150Hz. The time series of the main frequency is studied. It is found that the acoustic frequency of the main earthquake shifts from high value to low value during the pre-earthquake period, and the main frequency reaches a very low value. During the aftershock period, the main frequency rises from low value to high value, f_D and M_L have a power function relationship f_D = 130.7 × (M_L + 2) ~ (-0.3). The results show that the correlation between ground acoustic frequency and time and magnitude mainly depends on the source rupture scale and the stress state and the Q factor of quality factor. Near-field acoustic observations and research results of the 3.1-magnitude earthquake sequence are in good agreement with the experimental results of rock-burst processes and acoustic emission activities and spectral features at home and abroad in recent years. It shows that continuous near-field sounding and real-time analysis in mines and seismic activity areas are of great significance for the prediction of rockburst and seismic processes.