Unique topography of the Bhutan Himalaya: Implications for active tectonics (Nepal)

The Himalaya is the quintessential collisional orogen and is geologically young and tectonically active. The Himalayan tectonostratigraphic units can be traced throughout the 2500 km long arc, thus making the geology of northern India, Nepal, and Bhutan similar in many ways. However, recent seismic and geomorphologic studies have indicated significant geologic and topographic differences between the Himalayas of Bhutan and Nepal. The topography of Bhutan consists of two "lobes" of steep slopes, separated by a step of low slope and low relief. A slope map of Bhutan derived from the 90-m Shuttle Radar Topography Mission (SRTM) Digital Elevation Model (DEM) discriminates five physiographic transitions: PT1, PT2a, PT2b, PT2c, PT3, and a north-south trending discontinuity PT4. Integration of the topographic and geomorphologic results with earthquake locations will enable mapping of the previously unrecognized active faults in Bhutan. This can improve our understanding of the crustal structure of Bhutan, the local stress regime, and their implications to seismic and geologic hazards in the Bhutan Himalaya. (Abstract shortened by UMI.)...