HR: 0830h
AN: S21F-0398    [PDF]
TI: Results from a Temporary Seismic Network in Bhutan
AU: * Velasco, A A
EM: velasco@geo.utep.edu
AF: University of Texas at El Paso, Geological Sciences, El Paso, TX 79968-0555 United States
AU: Miller, K C
EM: miller@geo.utep.edu
AF: University of Texas at El Paso, Geological Sciences, El Paso, TX 79968-0555 United States
AU: Hollister, L S
EM: linc@princeton.edu
AF: Princeton University, Dept. Geology & Geophysical Sciences, Princeton, NJ 08544-3074 United States
AB: We report preliminary results from a five-station network deployed as a pilot experiment to examine seismicity patterns and lithospheric structure in central and western Bhutan. The seismic stations, comprised of equipment from the PASSCAL instrument pool, were installed in January of 2002 in cooperation with the Geological Survey of Bhutan and removed in March 2003. We are processing 14 months of data, and have detected both local and regional events. We located events and have computed magnitudes of these microearthquakes. Further analysis will allow for lithospheric studies, including velocity model development and receiver function and shear-wave splitting analysis. We attempt to identify the seismogenic structures in the region and to contribute to the understanding of the tectonic evolution of the region. The country of Bhutan lies in a relatively unexplored but geologically significant portion of the eastern Himalayas. Few geologists have entered the country, yet it lies in a strategic position near the south end of the INDEPTH seismic transect in Tibet. One model for ongoing deformation in the Himalayas has been derived from observations on and southward extrapolation of the INDEPTH profile. This model attributes the high mountains to accommodation of the Tibetan plate as it pushes over bends in a crustal ramp. This model essentially calls for brittle behavior of the entire crust under Bhutan. An alternate model derived from geologic studies in Bhutan calls on the southward extrusion within a channel from mid-crustal depths under Tibet to account for the high relief. This model predicts ductile deformation and thus little mid-crustal seismicity. With our results, we hope to gain insight into which deformation model, if either, is appropriate for this region of the Himalayas.
DE: 7215 Earthquake parameters
DE: 7223 Seismic hazard assessment and prediction
DE: 7230 Seismicity and seismotectonics
SC: Seismology [S]
MN: 2003 Fall Meeting