Coseismic movement of an active landslide resulting from the Mid-Niigata Prefecture Earthquake,Japan

摘要

The Mid-Niigata Prefecture Earthquake was an inland earthquake of magnitude 6.8 that occurredin the Niigata prefecture,Japan on October 23,2004. This earthquake triggered more than 4000 sedimentdisasters. The Busuno landslide research site is one of the landslides that were triggered by the earthquake. Wemonitored the surface displacements,the pore water pressures and the rainfall in the Busuno landslide by theearthquake every ten minutes. The earthquake caused the landslide displacement of 1.9 to 6.7 mm. A comparisonof this displacement with the displacement caused by rainfall before the earthquake showed a proportional matchin their respective distributions. The earthquake caused the pore water pressure to fluctuate between -0.96 to+ 1.22 kPa. However,the variations were not uniform. Considering the relationship between the distributionof landslide deformation and the pore pressure,it was concluded that the variation in pore water pressure wasgenerated by local compression or extension in the landslide mass.