Spatial correspondence between historical land modification and liquefaction-induced ground deformation during the 2024 Noto Peninsula Earthquake in Uchinada Town, Japan

Abstract

Abstract

Abstract Background The 2024 Noto Peninsula Earthquake ( $$M_\textrm{w}$$ 7.5) triggered liquefaction in 2114 grid cells (250-m mesh) across four prefectures and lateral flow along the southwestern margin of the Uchinada Sand Dunes, Ishikawa Prefecture, Japan, approximately 100 km from the epicenter. Despite the moderate seismic intensity of JMA 5-lower, ground deformation occurred in residential areas built on filled ground derived from sand dune excavation during the Kahokugata Reclamation Project (1963–1971) and earlier filling works. This study investigates the spatial correspondence between historical land modification and earthquake-induced ground deformation by combining multi-temporal digital surface models (DSMs) generated from historical aerial photographs via Structure from Motion–Multi-View Stereo (SfM-MVS), airborne laser survey data, and field investigations including surface wave exploration and particle size analysis. Results DSMs were generated from aerial photographs spanning five periods (1947, 1962, 1975, 2012, and 2024), and differentiated models revealed that excavation and filling had been conducted along Prefectural Route 8, with individual excavation zones extending 70–330 m (median 180 m) across the route, not only during the Kahokugata Reclamation Project (1963–1971) but also in the preceding (1947–1962) and following (1975–2012) intervals. Comparison of the identified excavation–filling boundaries with post-earthquake airborne laser survey data showed that ground subsidence initiated at or just beyond the excavation boundary in the two Area 1 cross-sections (within 2–3 m) but, in the three Area 2 cross-sections, intruded dune-side into the excavated body rather than starting at the boundary, while uplift occurred at the toe of the deformed slope in all sections. Across the mapped polygons, the co-seismic deformation zones overlapped historically excavated ground over 38% of their combined area (8% in Area 1, where deformation occupies the lowland between the excavation edge and the road, and 52% in Area 2). Field surveys confirmed lateral flow distances of 40–140 m across four districts, with the longest flow distance observed in Nishi-Araya, where excavation and backfilling had been performed. Surface wave exploration along cross-sections showed that low shear wave velocity zones ( $$V_\textrm{s} \approx $$ 100–130 m/s) at depths of approximately 3 m corresponded spatially to historically modified areas, consistent with poorly compacted fill identified in prior geotechnical investigations. Conclusions The multi-temporal SfM-MVS analysis revealed that excavation and filling along the southwestern margin of the Uchinada Sand Dunes occurred not only during the Kahokugata Reclamation Project (1963–1971) but also before (1947–1962) and after it (1975–2012); these pre- and post-project modifications had not been captured in existing construction records. The spatial distribution of co-seismic ground deformation was spatially associated with these historically modified areas: subsidence initiated at or just beyond the excavation boundary in Area 1 but intruded dune-side into the excavated body in Area 2, and uplift occurred at the toe of the deformed slope, typically terminating at PR8 or the adjacent unmodified lanes. The SfM-MVS-based retrospective topographical analysis thus provides a practical tool for identifying zones susceptible to liquefaction-induced lateral flow in coastal lowlands with comparable reclamation or fill histories, particularly where land modification records are incomplete or spread across multiple periods that are not documented as a single project.