In the 2011 off the Pacific Coast of Tohoku Earthquake, many slope disasters occurred on roads. For the road slope disaster prevention in the future, we collected and analyzed 168 cases of road slope disasters by this earthquake. In these 168 cases, collapses of embankment or road shoulder occurred most (46%), collapses of rock slope (large scale rock fall) occurred to the second much (28%), and and other cases were rock fall, collapse of soft earth (shallow landslide), landslide etc. About the volume of collapsed mass, 39% of the cases were within 100m3, 37% of the cases were 100m3 to 1000m3, 24% were over 1000m3. Landslide cases, particularly, contains large scale cases over 10000m3 in volume. JMA seismic intensity near the each site was 5 upper and over in almost all cases, and 6 lower in 65% of the cases. Collapses of rock slope occurred in the area of sedimentary and metamorphic rocks of Paleozoic to Mesozoic age, and 3/4 of these cases occurred on the ridge slope. Landslides occurred in the area of Neogene sedimentary and volcanic rocks, including many cases whose geological structure dip concordant to the slope, and cases occurred in the part of old landslide topography. In the area of granites, various type of disasters including collapses of rock slope, rock fall, collapse of soft earth etc. occurred. Many of collapses of embankment or road shoulder occurred at the site where water is likely to permeate such as embankment filling the valley. Moreover, past deformations or disasters have been recorded in 10% of the cases in this study. It needs to inspect and examine countermeasures against these sites particularly. |