HIMEX-A Broad Band Seismic Experiment Across Kumaon Himalaya

We present initial results from a dense seismic network in Kumaon Himalaya comprising of 25 broadband Guralp CMG-3T seismometer and REFTEK's RT130 data loggers recording earthquakes in continuous mode at 50 samples/s. The seismographs are placed mostly along a 150 km long SW -NE profile (29.80N, 78.54 E to 30.65N, 79.81E ) from Himalayan Frontal Thrust (HFT) in south to Southern Tibetan Detachment (STD) in the north at an average spacing of 10 km. Between MBT and MCT the stations are also deployed off the profile for better earthquake location and velocity imaging in the region. The experiment started in April 2005 and would continue for 24 months. Based on analysis of regional earthquakes Pn and Sn velocity of 8.4 and 4.7 km/s has been inferred. Using teleseismic receiver functions we model the Moho depth increasing from 40 km beneath HFT to 50km below MCT. Signature of underthrusted Indian crust is clearly visible in the receiver function as positive conversion. The differential time of this conversion increases from less than 1s in south to more than 2 s in the north of MCT.