TXT-tool 3.081-1.9: Dynamic Properties of Earthquake-Induced Large-Scale Rapid Landslides Within Past Landslide Masses
On October 23, 2004, an earthquake with a magnitude of 6.8 struck the central region of Niigata Prefecture. Several hundreds of earthquake-triggered landslides brought great damages to important public infrastructures and human lives. Among them, two large-scale rapid landslides, namely Higashi Takezawa and Terano landslides occurred within past landslide masses and blocked the river flows posing significant secondary risks to the society situated both downstream and upstream of the damped river site by dam failure. The paper seeks to examine triggering factors and interpret movement mechanisms of two landslides through ring shear tests on samples taken at landslide sites during a detailed field investigation. In order to reproduce exactly the landslide occurrences, real earthquake wave loading test and cyclic loading tests were performed on these samples. The test results revealed that those sand samples from both landslides are easily susceptible to sliding surface liquefaction phenomenon with very low final apparent friction angles, while the silt sample from Terano landslide did not show liquefaction behavior, indicating that the sliding surfaces of these rapid landslides must have been formed within the sand layer in the past landslide masses.
KeywordsHigashi Takezawa and Terano landslides Dynamic properties Ring shear apparatus Earthquakes Sliding surface liquefaction
This research was conducted as a part of Theme 2: Landslide Investigation of the 2004 Mid-Niigata prefecture earthquake disaster investigation by MEXT (Ministry of Education, Culture, Sports, Science and Technology, Japan) Special Coordinating Fund for Science and Technology. The authors acknowledge its special coordinating fund to conduct this investigation and thank all members of this investigation team for discussion. We are grateful for Dr. Gen Furuya and other post-doctoral students and graduate students of the Research Centre on Landslides, Disaster Prevention Research Institute of Kyoto University for cooperation in the field investigation and sampling.
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