Numerical Simulation of the Landslide and Tsunami Due to the 1741 Oshima‐Oshima Eruption in Hokkaido, Japan
Numerical Simulation of the Landslide and Tsunami Due to the 1741 Oshima‐Oshima Eruption in Hokkaido, Japan
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1741 年日本北海道大岛大岛喷发引发的山体滑坡和海啸的数值模拟
DOI：
10.1029/2018jb016166
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发表时间：
2019
期刊：
影响因子：
--
通讯作者：
Kawakami Gentaro
中科院分区：
文献类型：
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作者：
Ioki Kei;Tanioka Yuichiro;Yanagisawa Hideaki;Kawakami Gentaro
1741年大岛大岛火山（日本北海道西南部）爆发时的扇形崩塌在日本海引发了一场大海啸。海啸对沿着大岛（北海道）和津轻（本州）半岛造成严重破坏。1741年的海啸沉积物在北海道的奥走和桧山海岸被发现。在本研究中，我们使用改进的两层模型对1741年大岛-大岛大喷发产生的滑坡和海啸进行了数值模拟，以解释滑坡的沉积面积，历史记录中的海啸高度以及海啸沉积物的分布。根据大岛-大岛火山北方斜坡的测深数据估算了1741年滑坡造成的侵蚀和沉积面积。此外，扇区崩溃前的地形也已恢复。根据滑坡前后的水深差异，坍塌物的体积估计为2.2立方公里。基于这些数据，通过求解改进的两层模型方程对滑坡和海啸进行了数值模拟，该模型在下层的底部摩擦项中加入了曼宁公式。一个明显的摩擦角为2.5和曼宁的粗糙度系数为0.15被选为解释的沉积面积估计从水深分析和海啸沉积物的分布。计算的滑坡体厚度分布与沉积区的分布比较吻合。计算出的海啸高度与沿着日山海岸的历史记录相符。计算的海啸淹没区涵盖了沿着已确定的海啸沉积物的大部分分布。
Sector collapse during the 1741 eruption of Oshima‐Oshima volcano (southwestern Hokkaido, Japan) generated a large tsunami in the Japan Sea. The tsunami caused severe damage along the Oshima (Hokkaido) and Tsugaru (Honshu) peninsulas. Tsunami deposits due to the 1741 event were identified along the Okushiri and Hiyama coast in Hokkaido. In this study, we numerically simulated the landslide and tsunami generated by the 1741 Oshima‐Oshima eruption using an improved two‐layer model to explain the depositional area of the landslide, the tsunami heights written in historical records, and the distributions of tsunami deposits. Areas of erosion and deposition by the 1741 landslide were estimated from the bathymetric data on the northern slope of Oshima‐Oshima volcano. In addition, previous topography before the sector collapse was restored. From the bathymetry difference before and after the landslide, the volume of collapsed material was estimated at 2.2 km3. Based on those data, the landslide and tsunami were numerically simulated by solving equations of an improved two‐layer model that incorporates Manning's formula in the bottom friction terms of the lower layer. An apparent friction angle of 2.5 and a Manning's roughness coefficient of 0.15 were selected to explain the area of deposition estimated from the bathymetry analysis and distributions of tsunami deposits. The thickness distribution of the computed landslide mass fits relatively well with the depositional area. Computed tsunami heights match those from historical records along the Hiyama coast. Computed tsunami inundation areas cover most of the distributions of tsunami deposits identified along the coasts.