The landslide at Susobana was caused by the embankment to make a road. Analysis using the φ=0 method is carried out for the combined sliding surface with arcs and a plain. The undrained Shear strength that is needed to make a safety factor 1 is in accord with a result of laboratory test on the weathered mudstones.
The landslide at Makiuchi was caused by a high pore-water pressure due to Matushiro earthquakes. Calculations for the c', φ' analysis is made to investigate the values of excess pore-water pressures and it follows that the pore-water pressures acting on a part of sliding surface reached to 20-30m head.
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