Some Considerations on a Large Landslide at the Left Bank of the Aratozawa Dam Caused by the 2008 Iwate-Miyagi Intraplate Earthquake

摘要

The scale and impact of rock slope failures are very large and the form of failure differs depending upon the geological structures of slopes. The 2008 Iwate-Miyagi intraplate earthquake induced many large-scale slope failures, despite the magnitude of the earthquake being of intermediate scale. Among large-scale slope failures, the landslide at the left bank of the Aratozawa Dam site is of great interest to specialists of rock mechanics and rock engineering. Although the slope failure was of planar type, the direction of sliding was luckily towards the sub-valley, so that the landslide did not cause great tsunami-like motion of reservoir fluid. In this study, the author attempts to describe the characteristics of the landslide, strong motion and permanent ground displacement induced by the 2008 Iwate-Miyagi intraplate earthquake, which had great effects on the triggering and evolution of the landslide.