[H-DS07] Landslides and related phenomena

[HDS07-P10] Landslides damaged by repeated earthquakes - in the case of the slopes in Noto Peninsula -

*Issei Doi¹, Gonghui Wang¹, Shintaro Yamasaki¹, Hikaru Osawa², Gen Furuya³, Ryosei Oishi⁴ (1.Disaster Prevention Research Institute, 2.Forestry and Forest Products Research Institute, 3.Toyama Prefectural University, 4.Graduate School of Science, Kyoto University)

Keywords:earthquake-induced landslides

Although lots of researches have been conducted on the hazard mapping of slopes that collapse during earthquakes, it is not well known how the collapse volume and/or temporal changes in the risk of slope failure when repeatedly subjected to strong earthquakes are involved with the landslides. Earthquake swarm activity started in the Noto region of Ishikawa Prefecture since 2020, and two large earthquakes occurred on May 5, 2023 (Mj 6.5) and January 1, 2024 (Mj 7.6), with which Shoin-cho in Suzu City recorded a seismic intensity of 6+ for both earthquakes, and Otani-cho in Suzu City 5+ in 2023, and 6+ in 2024. It was found as a result of field surveys that several slopes suffered from both earthquakes. Such landslides had different failuer characteristics for the two large earthquakes: the different areas/volumes and the different displacements. These characteristics are considered from the prospectives of the seismic amplification characteristics and/of strength reduction due to strong motion.