Abstract
The water quality was surveyed in the 4 landslide areas in Niigata prefecture for the purpose of the research of underground water. The 5 elements, which were HCO3-, Cl-, SO4-- Ca+++Mg++ and Na+, were analyzed in the method of component analysis. In the result, the contribution of information is 87.3% with the first and the second principal axes. Drawn on the orthogonal plane with the principal axes, the sample points are classified into 3 groups. Mean while, the data which were sampled in 3 times on the same station make an triangle. The shapes of triangles are distinguished into 3 patterns.
