粤闽两省地下流体月异常频次叠加分析

Analysis of monthly abnormity frequency stacking of subsurface fluid of Guangdong and Fujian Province

分析了粤闽交界地区、粤闽两省1988年1月到2000年12月以及粤西地区1987年1月到2000年12月地下流体月异常频次叠加值。结果表明,以正常时段占总时长80～90%作为设定异常阈值的依据,除1997年5月福建永安ML5 6级地震外,粤闽两省及其沿海发生中强地震前地下流体月频次叠加值均出现异常。粤闽两省计算结果显示了4个比较明显的高值异常时段,其中3个异常时段后,紧跟着是粤闽两省ML≥5 0中强地震的活跃时段,且叠加值的"正常时段"、"异常时段"与地震平静期、活跃期对应较好,为未来的中强地震活动频度和强度的判断提供依据,但该方法会损失个别资料的短期异常。

The values of monthly anomaly abnormity frequency stacking (VMAFS for short) of subsurface fluid were studied in Guangdong and Fujian, the border area from January 1988 to December 2000, and West Guangdong from January 1987 to December 2000. The result shows that the VMAFS of subsurface fluid occurred anomaly before the moderate strong earthquakes occurring in Guangdong, Fujian and it's coastal areas except Yongan earthquake with ML56 in May 1997, regarding the normal periods occupying 80-90 percent of the whole periods as abnormal region value-enacting gist. The counting results of the VMAFS of Guangdong and Fujian show four clearer high-value of anomaly-centralization periods. Following three of the periods was the earthquake active period with ML50, and the normal period and the abnormal period of the VMAFS corresponded well with the earthquake active period and the quiet period in Guangdong, Fujian and it's coastal area. It provides a criterion for forecasting the frequency and the intensity of the future moderate strong earthquakes, but the VMAFS may loss short-term precursor anomalies of some data.