愛知県旧小原村の風化花崗岩類における崩壊発生密度の岩相関での比較

• 戸邉 勇人

  京都大学大学院理学研究科

• 千木良 雅弘

  京都大学防災研究所地盤災害研究部門

• 土志田 正二

  京都大学大学院理学研究科

書誌事項

タイトル別名

• Comparisons of Landslide Densities between Rock Types in Weathered Granitoid in Obara Village, Aichi Prefecture
• アイチケン キュウ オバラムラ ノ フウカ カコウガンルイ ニ オケル ホウカイ ハッセイ ミツド ノ ガンソウカン デノ ヒカク

抄録

In 1972, numerous numbers of shallow landslides were induced in granite and granodiorite areas by a heavy rainstorm in Obara village, Aichi prefecture, central Japan. We examined quantitatively the effects of petrologic types and precipitation amounts on the landslide distribution and densities in the disaster area. The landslide density in granite area was 293/km² and was larger than ten times of that in granodiorite area (13/km²), even though both the areas had experienced a strong precipitation of about 200mm per 5 hours. Landslide densities increased with the amounts of precipitation in the granite area, but did not in the granodiorite area. Investigation with airborne laser scanner and aero photographs was successively applied to detect landslides by the 1972 rainstorm and also preceding landslides in an area of 3km², which indicated that the above contrast of landslide densities had already existed before the 1972 disaster. The differences in landslide densities and in increase of landslide density according to the amount of precipitation between granite and granodiorite areas could result from the difference in weathering profiles of these two rocks. The most widely distributed granite in the surveyed area is weathered granite with grade D_H, (decomposed granitoid) and/or D_M (moderately weathered gruss), which likely is loosened with a well defined front and provides preferable conditions for landslide. In addition, a certain type of granite is micro-sheeted in the surveyed area, also providing a preferable condition for landslide occurrence. On the other hand, the most widely distributed granodiorite is of grade DL (strongly weathered saprolite), of which granodiorite is not likely loosened with a well-defined front. This may be the reason why fewer landslides occurred in the granodiorite area.

収録刊行物

• 応用地質

  応用地質 48 (2), 66-79, 2007

  一般社団法人 日本応用地質学会

キーワード

• 花崗岩類
• 風化
• 表層崩壊
• 岩種

詳細情報

• CRID: 1390001204095901696
• NII論文ID: 110006290537
• NII書誌ID: AN00026635
• DOI: 10.5110/jjseg.48.66
• ISSN: 18840973
• ISSN: 02867737
• NDL書誌ID: 8862047
• Web Site: https://ndlsearch.ndl.go.jp/books/R000000004-I8862047
• 本文言語コード: ja
• データソース種別:
  • JaLC
  • NDL
  • Crossref
  • CiNii Articles
  • KAKEN
• 抄録ライセンスフラグ: 使用不可