The effect of geotopology on seismic motion was investigated in order to understand the characteristics of seismic motion that triggered landslides on mountains during the Mid-Niigata Prefecture Earthquake in 2004. Three-dimensional models were made of two mountains where large-scale landslides occurred, and seismic response analysis of these models was carried out by elastoplasticity FEM. This analysis revealed the following characteristics: 1) The amplification of seismic acceleration depended on the size and shape of the mountain. 2) Both surface soil and geotopology affected the seismic motion distribution in the mountain. 3) A comparison of the strain on the ground derived from the seismic response analysis with the landslide distribution revealed that the landslide sources were located in places where the strain on the ground was large
In this study, the authors analyzed the movement properties of landslides and the characteristics of damage by investigating the damage to highways during a landslide in Ohto Village, Nara Prefecture, for which precise data until the landslide was available, and applied the concept of risk management to landslide . The study showed that prediction of movement based on precise field surveys was effective for mitigating the damage by the landslide . The authors also pointed out that preliminary risk control is insufficiently recognized and proposed a flow for executing risk management . The landslide was estimated to have caused a loss of about 1.5 billion yen in the regional tourist industry by an indirect effect of damage by rumors, showing that indirect effects are serious as well as direct effects in risk management of landslide.