1995年陡河地震前后小震震源参数及其相互关系

THE FOCUS PARAMETERS AND THEIR CORRELATION FROM SMALL EARTHQUAKES BEFORE AND AFTER THE 1995 DOUHE EARTHQUAKE

在震源谱的多台多震尾波解法的基础上 ,应用 Brune震源模型 ,求解 1 995年 1 0月 6日陡河 ML5.9地震前后在其周围发生的 48次小地震的震源因子和震源波谱 ,进而估算了地震矩、拐角频率和应力降 ,并讨论了它们之间的相互关系和在陡河地震前后随时间的变化 .结果表明 :小震震源因子表现出相当大的稳定性 ,震源因子的峰值频率和随频率的变化形态都很相似 .发现震前一年左右曾多次出现应力降较高的事件 .需要指出的是 ,考虑到应力降由地震矩和拐角频率计算得到以及地震矩和拐角频率的相关关系 ,实际上 ,这里的高应力降指的是拐角频率高于正常值的情形 .

Based on seismic source spe ctrum solution by multi station and multi event coda method, applying Brune seismic source model, we have got the source factors and spectra of 48 small earthquakes occurred before and after the Douhe earthquake of October 6 in 1995. The seismic moments, corner frequencies and stress drops are estimated from the spectra, and their correlation and variation with time before and after the Douhe earthquake are discussed. The results indicate that the source factors show good stability, their peak frequencies and variation with frequency appear quite similar. Some events with higher stress drops occurred about one year before the Douhe earthquake. Taking into account that the stress drop is calculated from seismic moment and frequency, as well as the correlation between them, we emphasis that the higher stress drop mentioned here just implies the higher corner frequency than the normal value.