[U-15] The 2024 Noto Peninsula Earthquake (1:J)

[U15-P103] Inventory map production of the 2024 Noto Peninsula Earthquake-caused landslides in and around Machinomachi, Wajima City and their geomorphological characteristics

*Hiroshi, P. Sato¹, Go Sato², Syoji Doshida³, Kazunari Hayashi⁴, Junko Iwahashi⁵, Masato Sato⁶ (1.College of Humanities and Sciences, Nihon University, 2.Tokyo City University, 3.National Research Institute for Fire and Disaster, 4.Okuyama Boring Co., Ltd., 5.Geospatial Information Authority of Japan (GSI), 6.National Research Institute for Earth Science and Disaster Resilience (NIED))

Keywords:landslide, slope failure, earthquake, Noto Peninsula, Airborne LiDAR survey, Aerial photographs

We interpreted aerial photos taken by Geospatioanl Information Authority of Japan (GSI), after the 2024 Noto Peninsula Earthquake. The study area is in and around Machinomachi, Wajima City where is one of the landslide-concentrated areas. We corrected and revised the slope failures and sediment-accumulated areas inventory polygon data (as of 22 Jan 2024), published by GSI; as a result of the correction and revision, the following polygons were obtained; 1) landslide scars (landslide source areas; 809 polygons), 2) landslide bodies (209 polygons), 3) slightly defined landslide bodies (79 polygons), 4) disrupted sediments accumulated areas (514 polygons), 5) transported areas (93 polygons), 6) shallow landslides (954 polygons). These items were classified more in detail. Focusing on the case of 1) above, it was found that landslide area ratio was increased in an exponential manner as the slope angle was increased. On the case of 4), it was also found that some of the accumulated sediments were turned into debris flow; this phenomenon is closely correlated with the fact that monthly precipitation 462.5mm in Dec 2023, Wajima City was 1.7 times higher than that monthly 278.4mm in Dec, climatological standard normal precipitation in the City. Though GIS analysis indicted that landslides occured frequently in volcanic rocks in Neogene, it is thought that thick siltstone overlain by the thin volcanic rocks is involved in some occurrences of the landslides in the study area, according to the outcrop observation at the landslide scars.