Batbileg BADRAKH

Analyzes of Geomorphological Characteristics of Earthquake Induced Slope Failures Within Landslides

Satoru OHTSUKA

This study investigates earthquake-induced landslides, focusing on two significant seismic events in Japan: the Niigata Chuetsu Earthquake in 2004 and the Noto Peninsula Earthquake in 2024. The primary objective is to examine the influence of geological factors and proximity to seismic fault lines on landslide occurrence rates within a seismically active region.

We conducted a comprehensive analysis of landslide incidents associated with both earthquakes, utilizing Geographic Information System (GIS) technology to map the distribution of landslides relative to their distances from seismic faults. Our findings reveal a significant correlation between distance from the fault and landslide occurrence, with the highest incidence observed within a 0-2 km radius, followed by a gradual decline in rates as distance increased.

A key aspect of this research was the comparison of landslide occurrence rates in areas defined as landslide terrain and those outside it. Landslide terrain areas, characterized by historical landslide activity and unstable slopes, show a higher likelihood of post-earthquake landslides. Conversely, areas outside this terrain, with no recorded landslide history, are comparatively stable but are still susceptible to landslides under extreme conditions. The internal landslide occurrence rate and the external landslide occurrence rate were computed using respective formulas, comparing the area of landslides to the total geological area in each region. 

Notably, distinct geological types, such as sandstone and alternating layers of mudstone and sandstone , were found to significantly affect landslide susceptibility, with deep-seated failures dominating landslide-prone regions while superficial failures were prevalent in more stable terrains. 

These insights contribute to a better understanding of the mechanisms behind earthquake-related landslides and offer valuable implications for disaster prevention and risk mitigation strategies in vulnerable regions.