Large-scale landslides in Toyama Prefecture, central Japan, and their probable relationship with earthquakes
Large-scale landslides in Toyama Prefecture, central Japan, and their probable relationship with earthquakes
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DOI：
10.1007/s12665-013-2654-y
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发表时间：
2014-03
影响因子：
2.8
通讯作者：
S. Kojima;T. Nozaki;Hidehisa Nagata;Ryota Tanahashi;R. Kondo;Noriaki Okamura;Kazuhiro Suzuki;A. Ikeda;Toshio Nakamura;T. Ohtani
中科院分区：
文献类型：
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作者：
S. Kojima;T. Nozaki;Hidehisa Nagata;Ryota Tanahashi;R. Kondo;Noriaki Okamura;Kazuhiro Suzuki;A. Ikeda;Toshio Nakamura;T. Ohtani
富山县库布苏河、贝索河一带的中新世伊万组发育大型滑坡，该组由安山岩熔岩、凝灰岩、凝灰岩角砾岩组成。在该组中部，凝灰岩容易蚀变为含蒙脱石岩，随后在滑坡事件的发展中起重要作用，这些事件往往是大规模的事件，因为上部段的块状熔岩在凝灰岩上形成盖层。基里塔尼盆地和科伊纳米盆地分别位于库布苏河和贝索河沿岸，是平坦的山间盆地，它们被解释为山体滑坡淤积的湖泊，后来被沉积物填满。加速器质谱14c年龄表明，形成每个大坝的滑坡同时发生，大约在2500 BP。这些年龄是根据基里塔尼滑坡材料中嵌入的木头碎片和Koinami蓄水期间淹没的原位树桩测量的。如果引发这些滑坡的是地震，那么很有可能是沿Atotsugawa断裂带发生的倒数第二次地震。
Large-scale landslides along the Kubusu and Besso rivers in Toyama Prefecture are developed in the Miocene Iwaine Formation, which is composed of andesitic lava, tuff, and tuff breccia. In the middle member of this formation, the tuff is easily altered to montmorillonite-bearing rock, and subsequently plays an important role in the development of landslides events, which tend to be large-scale events, as the massive lava of the upper member forms a cap rock over the tuff. The Kiritani and Koinami basins, which are flat intermontane basins located along the Kubusu and Besso rivers, respectively, are interpreted as landslide-dammed lakes, later filled with sediment. Accelerator mass spectrometry14C ages show that the landslides forming each dam occurred simultaneously, at approximately 2500 BP. These ages were measured from wood fragments embedded in the landslide material of Kiritani, and from an in situ stump drowned during the impoundment of Koinami. If the trigger of these landslides was an earthquake, it is most likely to have been the penultimate event along the Atotsugawa fault zone.