阿蘇火山・立野峡谷付近における滝の後退速度 Recession Rates of Waterfalls in and upstream of the Tateno Canyon, Aso Volcano

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著者

    • 早川 裕一 HAYAKAWA Yuichi
    • 東京大学大学院理学系研究科地球惑星科学専攻 Department of Earth and Planetary Science, Graduate School of Science, The University of Tokyo
    • 松倉 公憲 MATSUKURA Yukinori
    • 筑波大学大学院生命環境科学研究科地球環境科学専攻 Geoenvironmental Sciences, Graduate School of Life and Environmental Sciences, University of Tsukuba

抄録

Recession rates of two waterfalls, Ayugaeri Falls and Sugaru Falls, which are associated with the gorge formation of in the Tateno Canyon in the western part of the Aso caldera, are examined on the basis of the empirical equation after Hayakawa and Matsukura (2003). The waterfalls are postulated to have originated at a location out of the caldera as a waterfall which was formed around the front of the Akase lava erupted from the inside of the caldera. The initial waterfall receded about 2.8km upstream forming the gorge to the present site of the confluence of the Shirakawa River and the Kurokawa River in the caldera. At the confluence, the waterfall bifurcated into two waterfalls which continued recession along the Shirakawa River and the Kurokawa River to the present locations of the Ayugaeri and Sugaru falls. The recession rates estimated from the equation are 0.086m/y for Ayugaeri Falls and 0.143m/y for Sugaru Falls. The calculated time taken for the recession from the confluence to the present sites of the individual waterfalls is nearly equal : ca. 13,000y, indicating that the bifurcation of the waterfalls occurred about 13,000 years ago. Rough estimation suggests that the time for the initial waterfall to recede the distance of 2.8km is 14,000-28,000y. The total time of the waterfall recession from the start to the present location is thus 27,000-41,000y, which is consistent with the age of the Akase lava flow (ca. 30,000y).

Recession rates of two waterfalls, Ayugaeri Falls and Sugaru Falls, which are associated with the gorge formation of in the Tateno Canyon in the western part of the Aso caldera, are examined on the basis of the empirical equation after Hayakawa and Matsukura (2003). The waterfalls are postulated to have originated at a location out of the caldera as a waterfall which was formed around the front of the Akase lava erupted from the inside of the caldera. The initial waterfall receded about 2.8km upstream forming the gorge to the present site of the confluence of the Shirakawa River and the Kurokawa River in the caldera. At the confluence, the waterfall bifurcated into two waterfalls which continued recession along the Shirakawa River and the Kurokawa River to the present locations of the Ayugaeri and Sugaru falls. The recession rates estimated from the equation are 0.086m/y for Ayugaeri Falls and 0.143m/y for Sugaru Falls. The calculated time taken for the recession from the confluence to the present sites of the individual waterfalls is nearly equal : ca. 13,000y, indicating that the bifurcation of the waterfalls occurred about 13,000 years ago. Rough estimation suggests that the time for the initial waterfall to recede the distance of 2.8km is 14,000-28,000y. The total time of the waterfall recession from the start to the present location is thus 27,000-41,000y, which is consistent with the age of the Akase lava flow (ca. 30,000y).

収録刊行物

  • 地形

    地形 26(4), 439-449, 2005

    日本地形学連合

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被引用文献:  2件中 1-2件 を表示

各種コード

  • NII論文ID(NAID)
    110002238517
  • NII書誌ID(NCID)
    AN00333248
  • 本文言語コード
    JPN
  • 資料種別
    ART
  • ISSN
    03891755
  • NDL 記事登録ID
    7723394
  • NDL 雑誌分類
    ZM49(科学技術--地球科学--地質)
  • NDL 請求記号
    Z15-386
  • データ提供元
    CJP書誌  CJP引用  NDL  NII-ELS  IR  NDL-Digital 
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