HR: 16:30h
AN: S54A-05 [Abstracts]
TI: Geomorphic Features on the Movement of Reactivated Landslides due to Earthquakes
AU: * Moriwaki, H
EM: moriwaki@bosai.go.jp
AF: National Research Institute for Earth Science and Disaster Prevention, 3-1 Tennodai, Tsukuba, 305-0006 Japan
AU: Sasaki, Y
EM: s0323337@ipe.tsukuba.ac.jp
AF: Graduate School of Life and Environmantal Sciences, University of Tsukuba, 1-1-1 Tennodai, Tsukuba,
305-8572 Japan
AU: Hattanji, T
EM: hattan@atm.geo.tsukuba.ac.jp
AF: Graduate School of Life and Environmantal Sciences, University of Tsukuba, 1-1-1 Tennodai, Tsukuba,
305-8572 Japan
AU: Kogure, T
EM: tkogure@atm.geo.tsukuba.ac.jp
AF: Graduate School of Life and Environmantal Sciences, University of Tsukuba, 1-1-1 Tennodai, Tsukuba,
305-8572 Japan
AB:
Strong earthquakes with M6.8 (JMA at maximum) in the Chuetsu region, Niigata prefecture, Japan on October 23, 2004, generated a number of landslides around the epicenter. This region consists of Tertiary mudstone and sandstone, and was originally a
landslide-prone area. Some of the earthquake-induced landslides formed natural dams and merged houses under water. These
landslides derived from the reactivation of old landslide masses, according to the landslide maps (NIED). Topographic
analysis focusing on the landslide movement was carried out with landslide maps before and after the earthquakes. Slope of
source areas in the reactivated landslides ranged from 7 to 27 degrees. Equivalent coefficient of friction H/L, where H is
runout height and L is horizontal runout distance, was proportional to the slope of the source area in the reactivated
landslides. The regression line of the above relationship agreed well with that in original landslides. The width of
landslide mass expanded 1.2-1.3 times of the width before slide on average. This means that both original and reactivated
landslides had equality of motion. The results allow estimation of the runout distance and deposition area of future
landslides in this region.
DE: 1815 Erosion and sedimentation
DE: 1824 Geomorphology (1625)
DE: 7223 Seismic hazard assessment and prediction
SC: Seismology [S]
MN: 2005 Joint Assembly