Abstract: By using the method of membership function of fuzzy set, which is also called the direct method of fuzzy recognition, we have collected and analysed the data of ground-water level in more than 30 wells located in the Beijing-Tianjin-Tangshan area before and after the 1976 Tangshan earthquake (M = 7.8). The results obtained show that the long and intermediate-term anomalies of groundwater level in wells before Tangshan earthquake are difficult to discover but the short-term and imminent anomalies can be recognized obviously. Moreover, the more the time is closed to occurrence of great earthquakes, the more wells show underground level anomalies.

Key words: The fuzzy recognition of precursory anomalies, Tangshan earthquake, Groundwater level

摘要： 本文利用模糊集从属函数方法,处理了1976年唐山地震前后,京津唐辽地区30余眼井的地下水位资料,约6300多个观测数据。结果表明:在唐山地震之前,地下水位的趋势异常不明显;但在该次地震前存在着明显的短临异常,而且越接近于地震发生,异常井孔越多,越集中于震中地区。

关键词: 模糊集从属函数, 唐山地震, 地下水位