大同地震台水准形变异常调查与地震关系的研究

分析了大同地震台水准自观测以来的正常背景与异常变化，调查了环境变化(降雨、地下水、开采等)对观测值的影响。认为1983～1989年口泉断裂处于闭锁状态，年变速率平均为-0．7mm／a，1990年7月～1991年3月，断层出现加速活动，变化幅度为4．0mm，期间发生了1991年1月29日山西忻州5．1级地震和1991年3月26日大同阳高5．8级地震。震后曲线斜率仍然偏大，年变速率平均为-3．0mm／a，呈现新的背景值。1995年8月～1996年5月3日包头6．4级地震前，出现了异常加速—反向抬升的图象。异常加速幅度为-3．0mm，反向抬升2．0mm，这是自观测以来从未有过的现象。分析认为1990年和1995年下半年的加速变化与1991年大同—阳高5．8级地震和1996年包头6．4级地震有关。

Study on the relationship of the fixed leveling anomalies in Datong Seismostation with earthquakes

the normal background and variation of anomalies for fixed leveling observation are analyzed, and the environmental effect (rain, groundwater and mining, etc.) is investigated. The results shows that Kouquan fault was closedown during 1983 to 1989, for its annual rate was only 0.7mm/ya; the fault motion accelerated during Jul. 1990 to Mar. 1991 with an magnitude of 4.0mm; and during the period two earthquakes (Xinzhou 5.1, Jan. 29, 1991; Datong-Yanggao 5.8, Mar. 26, 1991) occurred. The slope of the observational figure still tends to large with a mean annual rate of -3.0mm/ya after the two events, which shows a new background. The figure showed acceleration (-3.0mm) and reversed rising (2.0mm), which is a phenomenon that have never been appeared before. We concluded that the acceleration in 1990 and the half year of 1995 is relevant to Datong-Yanggao 5.8 earthquake of 1991 and Baotou 6.4 earthquake of 1996 respectively.