Characteristics and controlling factors of landslides triggered by the 2024 Noto Peninsula Earthquake

On 1 January 2024, a MJMA 7.6 earthquake with a focal depth of approximately 16 km and a maximum seismic intensity of VII struck the Noto Peninsula of Japan. The strong seismic motion triggered at least 2,345 coseismic landslides. In this context, a detailed field survey and further correlation analysis were conducted in this work to investigate the spatial distribution, geometric feature, failure mode, and controlling factors of coseismic landslides. It is concluded that coseismic landslides spread in an elliptical area extending NEE/SWW, running approximately parallel to the strike of active faults in this region. Most coseismic landslides are distributed in areas where the epicentral distance is less than 53 km, PGA is greater than 0.5 g, and seismic intensity (MMI) is greater than 8.0. Coseismic landslides mainly occurred in strongly weathered and fractured rocks. Miocene sedimentary rocks and volcanic rocks are the predominant bedrock types identified in the landslide area. Coseismic landslides preferentially occurred in the area with an elevation between 100 m and 350 m, a slope angle between 20° and 40°, and a slope aspect from south to southeast (perpendicular to the strike of active faults). Most coseismic landslides are characterized by a small to medium scale with short run-outs and large mobilized apparent friction angles. Meanwhile, a comparison was also conducted between landslides triggered by the 2024 Noto Peninsula Earthquake and those by the 2018 Iburi earthquake. This work provides general insights into typical features of landslides triggered by the 2024 Noto Peninsula Earthquake.