TY - JOUR PY - 2008// TI - A channelised long run-out debris slide triggered by the Noto Hanto Earthquake in 2007, Japan JO - Landslides A1 - Okada, Yasuhiko A1 - Ochiai, Hirotaka A1 - Kurokawa, Ushio A1 - Ogawa, Yasuhiro A1 - Asano, Shiho SP - 235 EP - 239 VL - 5 IS - 2 N2 - A strong earthquake ( M J 6.9, M W 6.6-6.7) at about 11 km depth hit the western shore of the Noto Peninsula on Honshu, Japan, at about 00:42 coordinated universal time (9:42 a.m. local time) on 25 March 2007 (the Noto Hanto Earthquake in 2007). The earthquake triggered only 61 landslides, with most traveling short distances. It caused one long run-out landslide in the Nakanoya district of Monzen town, Wajima city, Ishikawa Prefecture, when a portion of a deep-seated landslide transformed into a moderate debris slide down a channel. The rock slide occurred on a south-facing convex-shaped slope on a small spur where earthquake ground shaking likely was strongly amplified by topography. A portion of the rock slide reached a small channel floored by materials containing abundant groundwater. Constant-volume box-shear tests on normally consolidated saturated specimens revealed that the apparent angle of internal friction of the channel-floor material was 33-36° at 10-mm shear displacement and did not show much decrease in effective normal stress during shearing. In situ rock-sliding testing on the exposed channel materials showed a low kinetic-friction angle of about 21°. We suggest that an unsaturated portion of the rock slide slid down the channel, with sliding between the rock-slide mass and the channel floor. Because the slope angle of the travel path nearly equaled the kinetic-friction angle, the unsaturated rock slide mass may have traveled at a moderately slow speed, or it might have decelerated and accelerated. Slow speed is supported by accounts from local residents that suggest movement of debris continued for 3 days after the main shock.

LA - SN - 1612-510X UR - http://dx.doi.org/10.1007/s10346-007-0090-3 ID - ref1 ER -