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.