TECHNICAL NEWS
VISIT OF ATC3 COMMITTEE ON SLOPE INSTABILITY SITES IN BHUTAN
Ikuo Towhata, University of Tokyo, towhata@geot.t.u-tokyo.ac.jp
Mitsu Okamura, Ehime University, okamura@cee.ehime-u.ac.jp
Hirofumi Toyota, Nagaoka University of Technology, toyota@vos.nagaokaut.ac.jp
INTRODUCTION
Asian member societies of ISSMGE have been operating several technical committees of their own and among those committees is ATC3 that concerns geotechnical natural hazards. In the current 4 years of term, this committee is chaired by Ikuo Towhata and is working on slope problems. As a part of the ATC3 activities, three committee members made a visit to Bhutan from October 18th, 2011, to 25th, and carried out some studies in collaboration with the Department of Geology and Mines of Bhutan Government and DHI-Infra Ltd.
Figure 1 illustrates the general idea of the Kingdom of Bhutan which ranges from the lowland at its Indian border to the top of Himalaya. The size of Bhutan is 38,400 km2 in area and its population is 700 thousands. Because of the tectonic action between the Indian Ocean Plate and the Eurasian Plate, the geology in Bhutan is highly distorted and fractured, which makes mountain slopes highly vulnerable to instability problems. The precipitation rate is 3,000 to 5,000 mm in the southern lowland, 1,200 to 2,000 mm in the lower Himalayan slopes, 500 to 1,000 mm in the central mountain regions, and less than 500 mm in Himalaya. Most precipitation takes place during the monsoon season of June to September.
Fig. 1 Map of Kingdom of Bhutan.
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