Sompi谱分析方法在处理数字地震记录中的初步应用

THE PRELIMINARY APPLICATION OF SOMPI SPECTRAL ANALYSIS METHOD IN PROCESSING DIGITAL SEISMIC WAVE RECORDS

使用数字地震记录,应用Sompi谱分析方法,对1989年1月—1990年7月发生在唐山地区的20个地震和1988年7月—1989年10月发生在大同周围地区10个地震波谱进行了分析,从而对1990年7月23日唐山M_L4.9地震和1989年10月19日大同M_L6.1地震P、S波频谱异常变化特征进行了研究。所得结果表明:地震前P、S波频谱的卓越频率f_d可能呈现出较明显的下降异常变化,因而它可能成为地震预报的有用指标;三分量呈现异常的时间基本上同步,并与用功率谱分析法得出的峰值频率f_m在数值上相近,在变化趋势上更为明显,因此,可以代替f_m;前震S波频谱的峰值频率f_d明显偏小,因而它可作为识别前震的重要指标。所以,可以将Sompi谱分析方法引入到数字地震记录资料处理中。

By using the digital seismic records and the method of Sompi spectral analysis, the P. S wave spectra of 20 earthquakes occurred in the Tangshan area during January 1989 to July 1990, and 10 earthquakes occurred in the area around Datong during July 1988 to October 1989 had been calculated and analyzed. Then, the anomalous variations in different characteristics of P, S wave spectra before the Tangshan earthquake (ML4.9), July 23, 1990, and the Datong earthquake (ML6.1), October 19, 1989 were studied. The results obtained show that before strong earthquakes the more remarkable decrease-type anomalous variations may be discovered in the domminant frequency fd of P, S wave spectra . Therefore, it may become an useful index for earthquake prediction, the precursory anomalous times of the 3-direction components ( SN, EW and UD) are basically synchronous and consitent with the perk frequency fm of power spectra calculated based on correlated functions, and the dominant frequency fd of S wave of foreshocks are obviously smaller, so they may be used as an important index for recognition of foreshocks.