@article{oai:niigata-u.repo.nii.ac.jp:00028042,
 author = {相楽, 渉 and 渡部, 直喜 and 佐藤, 修 and 丸井, 英明 and 垣原, 康之},
 journal = {新潟大学積雪地域災害研究センター研究年報, 新潟大学積雪地域災害研究センター研究年報},
 month = {Mar},
 note = {The Hieda-yama landslide area is located in the northwestern part of Nagano Prefecture. Landslides and debris flows have repeatedly occurred in this area. Bed-rock geology of this area is mainly composed of the Quaternary andesitic rocks. These andesites were weakly altered along joints and cracks in the rocks and are bearing secondary minerals such as pyrite, quartz and smectites. Ca and SO_4 ions of stream water are very concentrated in this landslide area. This fact suggests that the chemical weathering of andesitic materials is very active and the most important factor for occurrences of landslides and production of debris and soils. The chemical weathering in this area is dominated by the oxidation of pyrite, one of the secondary minerals by hydrothermal alteration. Rock forming minerals, particularly plagioclase are dissolved and their components are leached out by sulfuric acid formed by oxidation of pyrite. The annual rate of soil production by chemical weathering is estimated by using parameters such as average annual precipitation, catchment area, Ca concentration of stream water, density of soil and fresh andesite, and CaO content of fresh and weathered andesites.},
 pages = {83--96},
 title = {長野県稗田山崩壊地における安山岩の化学風化について(予報)  (大木靖衛教授退官記念号）},
 volume = {19},
 year = {1998}
}