Abstract: Based on careful selection of underground fluid observation wells(springs),and using the monthly means and subordinate function method,we select the precursory anomalies information of underground water level before the moderately strong earthquakes in Hainan and its vicinity from these wells(springs)and analyze the characteristics of these precursory anomalies.Anomalies in water level are categorized into two classes: ascending medium term anomalies and descending medium-short term anomalies.Statistics show that the average time of medium-short term anomalies in subordinate function is approximately one year before the earthquake,which can be used as reference time index for mid and short term earthquake prediction in this area.

Key words: earthquake precursor anomalies, well water level, medium term, medium-short term, subordinate function

摘要： 对海南地下流体观测井(泉)和测项进行严格筛选的基础上,运用月均值和从属函数异常判定方法,提取了所选井(泉)在海南及其邻近地区中等以上地震前出现的地下水位前兆异常信息,对前兆异常的特征做了分析研究。水位异常分为上升型中期异常和下降型中短期异常(即"破年变"异常)两类。从属函数中短期异常的平均超前时间在1 a左右,并可通过R值信息量检验,该时间可作为发震时间的中短期预测的参考性指标。

关键词: 地震前兆异常, 井水位, 中期, 中短期, 从属函数