摘要
本文使用数字地震记录，用相关函数谱分析方法计算功率谱，对１９８９年１月至１９９０年７月发生在唐山地区的２０个地震、１９８８年７月至１８９９年１０月发生在大同周围地区１０个地震及１９８９年２月至１９９０年１２月发生在常熟地区的２５个地震的Ｐ、Ｓ波谱进行了分析，从而对１９９０年７月２３日唐山ＭＬ＝４．９地震、１９８９年１０月１９日大同ＭＬ＝６．１地震及１９９０年２月９日常熟ＭＬ＝５．５地震前Ｐ、Ｓ波频谱异常变化特征进行了研究，所得结果表明：１．地震前Ｐ、Ｓ波频谱的峰值频率ｆｍ，拐角频率ｆｃ，相对频带宽度△ｆ，相对峰值Ｓｍ／ＳＯ以及高频段的斜率绝对值｜ｂ｜等特征量均可能呈现出较明显的下降异常变化，因而它们都可能成为地震预报的有用指标；２．各频谱特征量呈现异常的时间基本上同步，并与波速异常发展趋势基本相符；３．前震Ｓ波频谱的峰值频率ｆｍ及拐角频率ｆｃ都明显偏小，因而它们可作为识别前震的两个重要指标。
Power spectra have been calculated by spectrum analysing method of correlation function based on digital data in this paper. We have analysed P and S wave spectra of 20 earthquakes occurred from Jan. of 1989 to July of 1990 in Tangshan, 10 earthquakes from July of 1988 to Oct. of 1989 around Datong and 25 earthquakes from Feb. of 1989 to Dec. of 1990 in Changshu. P and S wave spectra anomalies before Tangshan earthquake with ML=4.9 on July 23, 1990, Datong ML=6.1 earthquake on Oct. 19,1989 and Changshu ML=5.5 earthquake on Feb. 9, 1990 have been studied which show following results:1. Remarkable decrease variations of characteristics, such as peak frequency fm, corner frequency fc, relative width of frequency domain △f,relative peak value of Sm/So, and |b| of slope in high frequency segment,may happen before earthquakes which could be taken as useful indexes for earthquake prediction.2. The characteristic anomalies are generally synchronous which are basically uniform with anomalies of wave velocity.3. The peak frequency fm and corner frequency fc of S wave spectra of foreshocks show remarkable decrease which are considered as two vital indexes to distinguish foreshocks.
出处
《地震研究》
CSCD
北大核心
1994年第4期319-329,共11页
Journal of Seismological Research
基金
国家地震局"八.五"重点项目
关键词
地震预报
前震
地震波谱
频谱分析
Foreshock
Earthquake wave spectrum
Spectral analysis
China
