Tatsuya SAITO

Quantification of Ground Deformation in the Nishiaraya District of Uchinada Town during the 2024 Noto Peninsula Earthquake

Takaaki IKEDA, Masataka SHIGA

Noto Peninsula Earthquake 2024 caused widespread liquefaction and lateral ground flow damage in Uchinada Town, Ishikawa Prefecture, located about 100 km southwest of the earthquake epicenter. This town is situated on coastal sand dunes, and liquefaction occurred mainly at the inland foot of these dunes, resulting in severe damage to houses, roads, and lifelines. Furthermore, large-scale artificial landform modifications have been carried out in this area in the past. Excavated sand from the inland side of the dunes was used to reclaim parts of Kahokugata Lagoon for agricultural development. Residential areas have been developed on these modified lands, where significant liquefaction and ground flow damages were observed during the earthquake. Therefore, it is important to quantitatively evaluate ground deformation associated with liquefaction and to examine its relationship with past landform modification.
This study focuses on the Nishiaraya district of Uchinada Town, where severe damage occurred. Ground deformation associated with liquefaction and lateral flow was quantified by calculating the difference between digital surface models (DSM) before and after the earthquake. The pre-earthquake DSM was generated from aerial photographs using the SfM-MVS technique, while the post-earthquake DSM was obtained using LiDAR SLAM measurements. Because the aerial photographs were not originally taken for DSM generation, marker installation and correction processing were conducted to improve the accuracy of the pre-earthquake DSM.
The results show that ground deformation ranging from approximately +0.8 m (uplift) to −0.5 m (subsidence) occurred along Prefectural Road No. 8 in the Nishiaraya district. Large deformation was observed near Nishiaraya Elementary School. This area was previously used as a sand mining site and later reclaimed, suggesting the presence of relatively weaker ground.