2024-03-28T23:16:35Zhttps://eprints.lib.hokudai.ac.jp/dspace-oai/requestoai:eprints.lib.hokudai.ac.jp:2115/759922022-11-17T02:08:08Zhdl_2115_20039hdl_2115_116Fluidized landslides triggered by the liquefaction of subsurface volcanic deposits during the 2018 Iburi-Tobu earthquake, HokkaidoKameda, JunKamiya, HiroMasumoto, HirokazuMorisaki, TomonoriHiratsuka, ToruInaoi, Chisakimetadata only accessCreative Commons Attribution 4.0 International450The 6.6 M-w Iburi-Tobu earthquake struck southern Hokkaido, Japan on 6 September 2018. The earthquake triggered widespread slope collapses in the hills near the epicenter, resulting in destructive landslides that killed 36 people. Volcanic deposits covering the region slid downhill in a flow-like manner suggestive of fluidized landslides. Here, we report a distinctive example of liquefaction in the field, which could be a prerequisite for the generation of fluidized landslides triggered by large earthquakes. In the scarp of a typical landslide, an altered halloysite-bearing volcanic layer is observed at a level almost coincident with the sliding surface. The layer is intensely undulating and can be divided into an upper clay-rich layer and a lower pumice-rich layer, suggesting that the altered layer had liquefied as a result of the strong coseismic ground motion. The layer had been soaked by heavy rainfall just one day before the earthquake and could have liquefied, producing a weak and slippery plane, resulting in the catastrophic landslides in this area.Nature Publishing Group2019-09-11engjournal articleNAhttp://hdl.handle.net/2115/75992https://doi.org/10.1038/s41598-019-48820-y2045-2322Scientific reports913119