Journal of Geological Society of India (Online archive from Vol 1 to Vol 78)

A. Paul ¹, H. R. Wason ², M. L. Sharma ², Charu C. Pant ¹, A. Nirwan ¹, H. B. Tripathi ¹

Affiliations
1 Department of Geology, Kumaun University, Nainital - 263 002, IN
2 Department of Earthquake Engineering, IIT, Roorkee - 247 667, IN

Abstract

The seismic data recorded by the 'Digital Telemetered SeismiC Network' (DTSN) in Kumaun Himalaya during the period May 1999 to November 2000 have been used to calculate some of the source parameters and to comment upon the seismotectonic activity in the Kumaun-Garhwal region of the Himalaya. The source parameters have been calculated using the Brune's model of the earthquake source. The earthquakes are found to have very low stress drops. The maximum stress drop is found to be 95 bars for an earthquake of magnitude 34 with focal depth of 23 4 km. The shallow focus events having low stress drop indicate that the crust has low strength to withstand the accumulated strain energy. An endeavour has been made to empirically correlate the seismic moment magnitude to the source parameters computed in this part of the Himalaya. The epicentral locations indicate that the Kumaun Himalaya region between Main Central Thrust (MCT) and Main Boundary Thrust (MBT) is a seismically active zone.

Keywords

Seismotectonics, Stress Drop Thrust, Kumaun Himalaya.

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