July 2012 Rainfall-induced Landslides at the Eastern Wall of Aso Caldera

Abstract

 Intense rainfall on 11-12 July 2012 triggered numerous landslides and associated lahars in Aso caldera, southwestern Japan. Several landslides were observed especially on grassy slopes of the eastern caldera wall. Most of the landslides were shallow soil slips (< 1-2 m thick) in unconsolidated fallout tephra layers overlying lava and welded Aso pyroclastic-flow deposits, and some landslides were mobilized completely into lahars, traveling a few kilometers along stream channels. Similar landslide and associated lahar disasters occurred at Aso Volcano in July 1990 and June 2001. The characteristics of landslides and lahars provide important information for preventing or mitigating future similar disasters in the Aso caldera region.
(Photograph & Explanation: Yasuo MIYABUCHI; Photographed on October 7, 2012)