河北张北M6.2地震前水准观测的前兆信息

对山西省地震局代县中心地震台的水准观测项目在1998年1月10日河北张北M6．2地震前的异常变化特征进行了分析。认为，张北M6．2地震前存在着大范围的应力积累、调整过程。代县台的7条水准测线均存在长、中期形变异常。异常时间大约1a～2a左右。异常幅度变化大。地震发生在测线观测曲线异常转折恢复的过程中。

Precursory Information before Zhangbei,Hebei,Earthquake of M6.2

Characteristic of anomaly variation in leveling data of Daixian Central Seismological Station of Seismological Bureau of Shanxi Province before Jan. 10, 1998 Zhangbei,Hebei, earthquake of M6.2 is analyzed. It is considered that there is a process of stress accumulation and adjusting in large region before the Zhangbei earthquake of M6.2. There is long and medium term deformation anomalies on all seven leveling lines in Daixian Seismological Station. Anomaly time is about 1 a-2 a and anomaly amplitude varies largely. The earthquake occurred in the process of turn and comeback of anomaly of line data curve.