[H-DS05_29AM1] Landslides and related phenomena

[HDS05-02] Landsliding phenomenon under abnormal weather conditions: a case study

*Gonghui WANG¹, Akira SUEMINE¹, Sumio MATSUURA¹, Kiminori ARAIBA² (1.Disaster Prevention Research Institute, Kyoto University, 2.National Research Institute of Fire and Disaster)

Keywords:Abnormal weather, air pressure, Rainfall, landsliding, groundwater table

To examine the initiation and movement mechanisms of landslides occurring during abnormal weather conditions, we have been monitoring a landslide on Nisenotani area in Miyazaki Prefecture, Japan. The monitoring items include the weather conditions (rainfall and air pressure), moisture content of surficial soil layers, groundwater table, and displacements (by means of borehole wire extensometer, surficial extensometer, and total station). Cracks appeared on the slope after a heavy rainfall and borehole investigation revealed that this landslide is a large compound one, consisted of several sub-blocks. Our dense monitoring is performed on a small block of the toe part, and our results showed that: (1) landsliding was initiated by a heavy rainfall, but was not less affected by small rainfall; (2) landsliding varies with air-tide; (3) lower part of the sliding sub-block had been continuously compressed; (4) the sliding surface and the compressed soil layer had been effectively identified by means of a surface-wave technique.