Topographic effects on frequency-size distribution of landslides triggered by the Hokkaido Eastern Iburi Earthquake in 2018

摘要: This study examined the frequency-size distribution of 6117 landslides spread over 440 km2 in Iburi Subprefecture, Hokkaido, Japan, induced by Hokkaido Eastern Earthquake (Mw 6.6) on September 6, 2018. The area is characterized gently undulating terrain that finely dissected shallow streams and covered predominantly layers volcanic products with high water content. Most were landslides, their slip surfaces often formed a layer soil called “Ta-d,” deposited at 9000 ybp. Low ridges separating small catchments allowed individual to coalesce many locations. average size was 7160 m2. Landslide tended increase slope angle up 20° 25° then decrease further angle. About half occurred feature both concave planform profile curvature, 8720 In contrast, 17% total case curvatures being convex, 5190 results indicated accumulation saturated features provided more opportunities for large sizes. presented rollover, 5.0 × 10−3 km2, but exponent power law decay medium − 2.46, not largely different from those studies other Compared seismically caused examples, triggered can be as clustered, numerous, larger moment magnitude earthquake. Conversely, scale landslide event estimated equivalent region struck an earthquake Mw = 7.0 7.4. demonstrated regions produce unexpectedly frequent when intense earthquake, vulnerable ground shaking cover ground.