A Case Study of Behavior Observation of Landslide Induced by Snowmelt After an Earthquake

The landslide movement was recognized on April 19th, 2011 in Shimizu, Tokamachi city after the earthquake of M6.7 with the epicenter in Sakae village, Nagano Prefecture, occurred on March 12th, 2011. This landslide was probably induced by the snowmelt after the earthquake. This landslide is a reactive landslide, and the bedrock of this landslide is the Pliocene mudstone. The size of this landslide block is 100 m in width, 500 m in length, and 20 m in depth. Only this landslide greatly acted though a lot of landslide blocks were distributed around this landslide. To estimate the risk for the construction work of disaster recovery, the displacement monitoring using GPS and the groundwater level observation were executed in advance. The displacements were only detected when it rained heavily. The advanced landslide monitoring system performed in this case was effective to investigate for the disaster recovery safely because participants can share remotely landslide displacement data on semi-real time.