2:00 PM - 2:15 PM
[SSS14-14] Survey of the low terraces in the Noto Peninsula -Topography and surface structure around Yoshihura and OSL dating results in northeastern area-
The 2024 M7.6 Noto Peninsula earthquake occurred along an active fault located off the coast of the Noto Peninsula, causing the coastline to uplift by more than 4 meters at its maximum. In Shishikura et al. (2020), the distribution of low-level marine terraces (referred to as low marine terraces here) that are believed to have formed due to past earthquakes was examined through aerial photo interpretation. Three levels of low marine terraces (L1 to L3, from the highest) were identified, and the terrace surface elevations before the 2024 earthquake were determined using GNSS surveys with VRS-RTK at each site. However, challenges remain in quantifying the uplift rate and average fault displacement velocity, as the dates of emergence for the low marine terraces are still unknown, and the secondary effects such as artificial modifications to terrace surfaces have not been adequately assessed.
In this study, we focused on the westernmost site where lo marine terraces were identified by Shishikura et al. (2020), and where a peak in crustal deformation during the 2024 earthquake was observed through synthetic aperture radar analysis (Geospatial Information Authority of Japan, 2024). The study area includes Yoshihura and Igis in Wajima City. To estimate the uplift rate in greater detail using terrace landforms, drone LiDAR surveys and simple excavations with hand augers were conducted in this region. Additionally, sand layer samples collected from the simple excavations were examined under a microscope to investigate the depositional environment of the low marine terrace formation layers.
Moreover, pit excavation with small backhoe or shovel (up to 1–2 m in depth), hammer coring, and hand auger (up to 3 m in depth) wereconducted at five locations: Orito, Takaya, Kataiwa in Suzu City, and Sosogi and Nafune in Wajima City (Shishikura et al., to be presented at the 2025 conference). In these investigations, dating samples were collected at Orito, Takaya, and Nafune, and luminescence dating was performed.
This presentation reports the detailed topography and shallow structure at Yoshiura and Igisu in Wajima City, and the results of excavation surveys and luminescence dating obtained from Orito, Takaya, Kataiwa in Suzu City, and Sosogi and Nafune in Wajima City.
In this study, we focused on the westernmost site where lo marine terraces were identified by Shishikura et al. (2020), and where a peak in crustal deformation during the 2024 earthquake was observed through synthetic aperture radar analysis (Geospatial Information Authority of Japan, 2024). The study area includes Yoshihura and Igis in Wajima City. To estimate the uplift rate in greater detail using terrace landforms, drone LiDAR surveys and simple excavations with hand augers were conducted in this region. Additionally, sand layer samples collected from the simple excavations were examined under a microscope to investigate the depositional environment of the low marine terrace formation layers.
Moreover, pit excavation with small backhoe or shovel (up to 1–2 m in depth), hammer coring, and hand auger (up to 3 m in depth) wereconducted at five locations: Orito, Takaya, Kataiwa in Suzu City, and Sosogi and Nafune in Wajima City (Shishikura et al., to be presented at the 2025 conference). In these investigations, dating samples were collected at Orito, Takaya, and Nafune, and luminescence dating was performed.
This presentation reports the detailed topography and shallow structure at Yoshiura and Igisu in Wajima City, and the results of excavation surveys and luminescence dating obtained from Orito, Takaya, Kataiwa in Suzu City, and Sosogi and Nafune in Wajima City.