双子地震P波谱比在地震短期预报中的应用研究

应用法国地震学家G.Poup inet等关于双子地震的有关理论,对云南地震台网数字地震资料开展应用研究,通过基线校正、数字滤波、波形对比等方法获得8对3级双子地震和武定地震易门台7对双子地震。对以上双子地震取起始3秒P波作富氏谱分析后进行谱比对数的斜率拟合。结果显示,由发生在6.5级姚安地震前7个月之内与之外时段的地震构成的双子地震,其P波谱比对数斜率绝对值都达到0.030以上,明显高于均由震前7个月之外发生的地震构成的双子地震谱比对数斜率;在距主震2°范围以内的台站可观测到双子波发生的变化。常熟台双子地震P波谱比对数斜率时间进程在南黄海地震发生之前也存在这一现象,但出现异常的时间扩大到9个月之内。

Research on Short Term Earthquake Prediction by P-wave Spectral Ratio of Earthquake Doublet

We have studied the data from the digital earthquake net of Yunnan province using the earthquake doublet theory proposed by French seismologist G.Poupinet and his co-workers.Eight groups of multiplet and seven groups of doublet of Wuding earthquake have been obtained from observations at Yimen station by baseline correction,digital filter and waveform contrast,etc.The Fourier transformations of these doublets are calculated individually with respect to the initial 3s from the P-wave arrival and the slope of decimal logarithms of spectral ratios versus frequency is estimated.The results show that absolute values of P-wave spectral ratio slop are all more than 0.030 for the earthquake doublets with one event occurring 7 months before the Yao′an M_L6.5 earthquake and the other occurring outside that period,significantly higher then the earthquake doublets preceding the Yao′an earthquake by more than 7 months.The variation in spectral ratio slop is observed in a sector of azimuth around 2° of the main shock.The doublets observed on Changshu Station following the South Yellow Sea middle-intense earthquakes show such variations in spectral ratio slope,but the time scale of one event of the doublets extends to 9 months before the main shock.