关键词: 活断层, 阶, 区, 地球化学场异常带

Abstract: The ionic content of groundwater increases gradually from the east to the west along the Haiyuan active fault. In the same hydrogeological conditions it is obviously higher on the segments which have high seismicities and larger displacement. There are regularities in the distribution of the components of gas in the overlying soil within the fault zone. The farther distance from the fault,the fewer the element content is. An anomalous zone of higher value is formed in the vicinity of the fault. The highest points,however,are not located entirely on the fault. In extension area,there is a bigger anomaly in amplitude of the contents of Rn,Hg and H. In compressional area,the largest anomalies of Hg and H appear at the segment which has the biggest displaument. The content of H changed obviously before and after the occurrence of Lingwu Earthquake.

Key words: Active fault, Stepping area, Geochemical fielld, Anomalous zone