从1984年以来,唐山台短基线、短水准观测已经持续了20多年,从数据的日变化曲线可以明显发现其经历了三个阶段,即1984-1989年、1990-1998年、1998年至今.与此分段特征相一致的还有华北大面积水准观测数据计算结果.本文使用季节-趋势分解方法(Season-Trend on Loess,STL),将原始观测数据分解为季节项、趋势项和残差项.由季节项中发现不同测段隐含的周期成分,从趋势项的变化寻找造成这种趋势变化的可能原因.经分析表明,在发生趋势性变化的时间点,发生了1989年大同6.2级地震、1991年的大同6.1级地震、1995年的唐山5.0级地震、1998年的张北6.2级地震和2004年的唐山4.9级地震.初步推测认为,台站数据的趋势变化与这些地震的孕育、发生有关.%The observation of short-baseline and short-leveling has been continuing for more than 20 years since 1984 at Tangshan station. And it is clear from the leveling data that there are three periods: 1984—1989, 1990—1998, and 1998 till now. Here the Seasonal-Trend on Loess (STL) method is used to decompose the observation data into season variation, trend and residual. From the seasonal series, the yearly period can be clearly found in all observation and there seem to be more than one factor which has the period of one year. From the trend series, the synchro-changes have been shown and the synchrochanges occurred at the wide-range leveling observation. At the same time, there are some earthquakes: Datong earthquakes (M6.1) in 1989 ＆ 1991, Tangshan earthquake (M5. 0) in 1995, Zhangbei earthquake (M6.2) in 1998, and Tangshan earthquake (M4.9) in 2004. It seems that the synchro-changes in the trend series of the short-leveling and shortbaseline data can be explained by these earthquake preparations.
展开▼
