Estimating the Topography Before Volcanic Sector Collapses Using Tsunami Survey Data and Numerical Simulations
Estimating the Topography Before Volcanic Sector Collapses Using Tsunami Survey Data and Numerical Simulations
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DOI：
10.1007/s00024-017-1589-8
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发表时间：
2017-08
影响因子：
2
通讯作者：
Y. Yamanaka;Y. Tanioka
中科院分区：
文献类型：
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作者：
Y. Yamanaka;Y. Tanioka
大型板块崩塌和山体滑坡有可能造成重大灾害。因此，在崩塌之前估算地形和条件，例如体积，对于分析崩塌材料的移动行为和危害风险是重要的。本研究考虑了日本历史上三次引发海啸的火山板块崩塌：1640年的Komagatake火山、1741年的大岛-大岛火山和1792年的云禅山- mayuyama火山。首先根据假定的崩塌情景对每一事件所产生的海啸进行了数值模拟。本研究的主要目的是基于这些结果和海啸调查数据的地形反演模型来呈现与事件发生前的地形相关的条件。先前许多研究的主题——大岛-大岛海啸，首先进行了模拟，以验证模型的准确性，并评估在模拟过程中，随着地形条件的变化，助跑高度如何变化。爬升高度对坍塌体积和摩擦加速度的影响尤为敏感；然而，观察到的助跑高度可以在适当的摩擦加速度条件下以高精度再现，即使它们不精确。介绍了崩塌体积产生观测到的上升高度的最小要求，并利用海啸数值模拟的结果进行了定量评价。据估计，Komagatake火山和云禅山- mayuyama火山的最小崩塌体积分别约为1.2和0.3 km3。
Large sector collapses and landslides have the potential to cause significant disasters. Estimating the topography and conditions, such as volume, before the collapse is thus important for analyzing the behavior of moving collapsed material and hazard risks. This study considers three historical volcanic sector collapses in Japan that caused tsunamis: the collapses of the Komagatake Volcano in 1640, Oshima–Oshima Island in 1741, and Unzen–Mayuyama Volcano in 1792. Numerical simulations of the tsunamis generated by each event were first carried out based on assumed collapse scenarios. The primary objective of this study is to present conditions related to the topography before the events based on inverse models of the topography from those results and tsunami survey data. The Oshima–Oshima Tsunami, which is the subject of many previous studies, was first simulated to validate the model accuracy and evaluate how run-up heights changed during the simulation as the topographic conditions changed. The run-up height was especially sensitive to the collapsed volume and frictional acceleration affecting the collapsed material; however, the observed run-up heights could be reproduced with high accuracy using proper conditions of frictional acceleration for the scenarios, even if they were not exact. A minimum requirement for the collapsed volume to generate the observed run-up height was introduced and quantitatively evaluated using the results of numerical tsunami simulations. The minimum volumes of the collapses of the Komagatake and Unzen–Mayuyama volcanoes were estimated to be approximately 1.2 and 0.3 km3, respectively.