5:15 PM - 6:45 PM
[U15-P100] Analysis on Characteristics of Slope Failures induced by the 2024 Noto Peninsula Earthquake
★Invited Papers
Keywords:landslide, GIS, slope angle, slope direction, geological features, distance from earthquake fault
On January 1, 2024, a large earthquake with a maximum intensity of 7 on the Japanese seismic intensity scale occurred in the Noto region of Ishikawa Prefecture, resulting in tsunamis, crustal deformation, and liquefaction. The earthquake also caused extensive damage including slope failures, landslides, and landslide dams, impacting lives, residences, and infrastructure.
In response, the Japan Society of Erosion Control Engineering initiated an emergency investigation committee to assess landslide disasters. Aerial photographs and LiDAR-derived topographic surveys were utilized to identify landslide sites across five study areas within the northern Noto Peninsula: (1) Monzen Town coastal area (38. 8 km2), (2) R249 coastal area (84.4 km2),(3) upper Machino River reaches (25.5 km2), (4) the Suzuya River and Teraji River basins (22.3 km2), and (5)Ukai River basin (32.5 km2).
Comparative analysis revealed consistent landslide area averages of 1000-1500 m2 across all areas. However, the Suzuya River and Teraji River basin exhibited the highest landslide area ratio at 1.91%, followed by the Ukai River basin (0.67%), Monzen Town (0.58%), R249 coastal area (0.43%), and upper Machino River reaches (0.27%).
Furthermore, landslide area ratios varied concerning geological features, with lava and pyroclastic rocks consisting of dacite and rhyolite of Cenozoic-Tertiary-Miocene age (N1_vas_al) showing elevated ratios, notably in the Suzuya River and Teraji River basins (2.7%) and the Ukai River basin (1.0%). Conversely, Monzen Town exhibited a high landslide area ratio in non-marine sandstone or sandstone/mudstone formations of Cenozoic-Paleogene Oligocene age(Pg4_sns) at 1.0%.
Analysis of landslide area ratios by slope gradient indicated peaks within the 45-55 degree range across all areas.
Although it is said that landslides tend to occur on convex slopes during earthquakes, no clear correlation between mean curvature and landslide area ratio was observed.
Regarding slope direction, with the exception of Monzen Town, t southeast-facing slopes perpendicular to the nearest active fault exhibited the highest landslide area ratios, followed by north to northwest directions. Monzen Town's landslide area ratios were significant across a wide range of directions, primarily from east to south and southwest.
In terms of the relationship between the distance from the earthquake fault and the landslide area ratio, the landslides extended up to 14 km away from the fault, and the landslide area ratio generally tended to decrease with the distance from the fault in each area.
Additionally, while no clear relationship between earthquake acceleration and landslide area ratio was found in Monzen Town, the other four areas exhibited maximum landslide area ratios at composite accelerations of 1000-1300 gal from the two horizontal components.
This comprehensive analysis provides valuable insights into the characteristics and predispositions of landslide occurrences in the wake of seismic events, contributing to enhanced disaster preparedness and mitigation strategies.
In response, the Japan Society of Erosion Control Engineering initiated an emergency investigation committee to assess landslide disasters. Aerial photographs and LiDAR-derived topographic surveys were utilized to identify landslide sites across five study areas within the northern Noto Peninsula: (1) Monzen Town coastal area (38. 8 km2), (2) R249 coastal area (84.4 km2),(3) upper Machino River reaches (25.5 km2), (4) the Suzuya River and Teraji River basins (22.3 km2), and (5)Ukai River basin (32.5 km2).
Comparative analysis revealed consistent landslide area averages of 1000-1500 m2 across all areas. However, the Suzuya River and Teraji River basin exhibited the highest landslide area ratio at 1.91%, followed by the Ukai River basin (0.67%), Monzen Town (0.58%), R249 coastal area (0.43%), and upper Machino River reaches (0.27%).
Furthermore, landslide area ratios varied concerning geological features, with lava and pyroclastic rocks consisting of dacite and rhyolite of Cenozoic-Tertiary-Miocene age (N1_vas_al) showing elevated ratios, notably in the Suzuya River and Teraji River basins (2.7%) and the Ukai River basin (1.0%). Conversely, Monzen Town exhibited a high landslide area ratio in non-marine sandstone or sandstone/mudstone formations of Cenozoic-Paleogene Oligocene age(Pg4_sns) at 1.0%.
Analysis of landslide area ratios by slope gradient indicated peaks within the 45-55 degree range across all areas.
Although it is said that landslides tend to occur on convex slopes during earthquakes, no clear correlation between mean curvature and landslide area ratio was observed.
Regarding slope direction, with the exception of Monzen Town, t southeast-facing slopes perpendicular to the nearest active fault exhibited the highest landslide area ratios, followed by north to northwest directions. Monzen Town's landslide area ratios were significant across a wide range of directions, primarily from east to south and southwest.
In terms of the relationship between the distance from the earthquake fault and the landslide area ratio, the landslides extended up to 14 km away from the fault, and the landslide area ratio generally tended to decrease with the distance from the fault in each area.
Additionally, while no clear relationship between earthquake acceleration and landslide area ratio was found in Monzen Town, the other four areas exhibited maximum landslide area ratios at composite accelerations of 1000-1300 gal from the two horizontal components.
This comprehensive analysis provides valuable insights into the characteristics and predispositions of landslide occurrences in the wake of seismic events, contributing to enhanced disaster preparedness and mitigation strategies.