阿蘇カルデラ壁斜面における斜面崩壊の発生頻度  [in Japanese] Recurrence interval of shallow landslides at the caldera wall slopes of Aso volcano, Central Kyushu, Japan  [in Japanese]

Access this Article

Search this Article

Author(s)

Abstract

<p>阿蘇カルデラを構成する急崖直下に広がる沖積錐には,安山岩・溶結凝灰岩・テフラ層のブロックなどを含む淘汰不良の堆積物が分布している.これらの堆積物の堆積時期を検討するため,5地区において,炭質物3点と古土壌4点のAMS <sup>14</sup>C年代を測定した.その結果,過去約2.6万年前まで遡る年代値が得られた.これらの<sup>14</sup>C年代値とテフラから,この5地点では過去約2.6万年間に,崩壊起源の土砂堆積イベントが少なくとも15回程度あったことが推定された.阿蘇カルデラの急崖では,過去2.6万年において,およそ10<sup>3</sup>年に1回のオーダーで,豪雨または強い地震動,あるいは両者の組み合わせを誘因とする崩壊堆積物が供給されてきたと推定できる.</p>

<p>Colluvium deposits distributed at the foot of the caldera wall of the Aso volcano are estimated to be piled-up materials derived from steep slopes. They are composed of poorly sorted gravel beds including andesite, welded tuff, and tephra blocks, and form sharp alluvial cones. Therefore, numerous shallow landslides caused by heavy rainfall and/or large earthquake vibrations may have brought about these deposits after the completion of the caldera wall.</p><p>In order to determine the ages of depositional events of such materials, we carried out the dating of three charred materials and four paleosols collected from the colluvium deposits. Calendar-calibrated AMS <sup>14</sup>C dating indicates that more than 15 depositional events occurred during the past 26,000 years at five investigation points. Based on this relation, the recurrence interval of such events is estimated to be on the order of 10<sup>3</sup> years in this area.</p>

Journal

  • The Quaternary Research (Daiyonki-Kenkyu)

    The Quaternary Research (Daiyonki-Kenkyu) 58(2), 149-162, 2019

    Japan Association for Quaternary Research

Codes

  • NII Article ID (NAID)
    130007659559
  • NII NACSIS-CAT ID (NCID)
    AN0034136X
  • Text Lang
    JPN
  • ISSN
    0418-2642
  • NDL Article ID
    029655461
  • NDL Call No.
    Z15-67
  • Data Source
    NDL  J-STAGE 
Page Top