云南水汞在打破M≥5级地震平静后强震前的异常分析

ANOMALY ANALYSIS ON MERCURY IN GROUND-WATER BEFORE STRONG EARTHQUAKES AFTER BREAKING QUIESCENCE OF Ms≥5

通过普洱6 3、宁蒗6 2级和姚安6 5级3个在省内M≥5级地震平静了10余个月,打破5级平静后发生的M≥6级强震前水汞的异常分析,并着重短临异常研究,结果表明这3次地震前水汞均有中期和短、临异常,中、短、临异常台站数为两头少,中间多。中期异常表现为11%～22%的水汞观测台站震前出现2～10个月的中期异常;短期异常表现为震前2～3个月,平均44%的台站观测到短期异常,最大异常幅度与异常判定线比值在1 3～3 2倍之间:强震前都只有1个台站出现临震异常。短期异常有差异,宁蒗6 2级主震前,短期异常在2次前震前出现,普洱6 3、姚安6 5级地震前,水汞短期异常在打破5级平静的地震前出现,水汞短期异常有活跃、平静的现象。最早出现中期异常的台站相对靠近震中。

Through anomaly analysis on mercury in groundwater after breaking quiescence of M≥5 for 10 months before Pu'er Ms6.3,Ninglang Ms6.2 and Yao'an Ms6.5 earthquakes,the short-impending anomaly has been studied.The results show that there appear anomalies of mid-term,short and impending terms of the mercury in groundwater.The number of stations with mid-short-impending anomalies shows the feature of less in two ends and more in the middle.It indicates that 2～10 months mid-term anomalies appear in 11%-22% of the observatories of mercury .The short-term anomalies were observed in 44% of stations 2～3 months before strong earthquakes.The ratio of maximum anomaly amplitude to the anomaly determining line is 1.3～32 times.The impending anomalies only appear in one station.The mid-anomalies are different from each other.Before Ninglang Ms6.2 main shock,the short-term anomalies appeared before two foreshocks.The short-term mercury anomalies appeared after breaking quiescence of Ms5 before Pu'er Ms6.3 and Yao'an Ms6.5.The mercury short-term anomaly has active and quiet phenomena and the station appearing mid-term anomalies at the earliest time is relatively closed to the epicenter.