| Autor: |
Ioki, Kei, Tanioka, Yuichiro, Yanagisawa, Hideaki, Kawakami, Gentaro |
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| Zdroj: |
Journal of Geophysical Research. Solid Earth; Feb2019, Vol. 124 Issue 2, p1991-2002, 12p |
| Abstrakt: |
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. Key Points: Model estimation to explain the depositional area of the landslide, the tsunami heights, and the distributions of tsunami depositsImproved two‐layer model to represent the submarine movement of the soil massThe initial movement of the landslide is important in predicting the size of the generated tsunami [ABSTRACT FROM AUTHOR] |
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Complementary Index |
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