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Authors
Affiliations
1 Geoscience Division, Regional Research Laboratory, Jorhat - 785006, Assam, IN
2 Dept. of Applied Geology, Dibrugarh University, Dibrugarh - 786004, Assam, IN
Source
Journal of Geological Society of India (Online archive from Vol 1 to Vol 78), Vol 58, No 4 (2001), Pagination: 285-301
Abstract
A study of travel times for Pg, P* and Pn waves is conducted for the three profiles along the Main Central Thrust (MCT) and Main Boundary Fault (MBF) in the Arunachal Himalaya and the Brahmaputra Lineament (BPL) in Assam, in order to obtain seismic velocities and the thicknesses of the upper and lower crust and the depth to Moho. These profiles roughly pass through the locations of seismic stations and the epicentres of the earthquakes used in this study. 143 earthquakes with magnitudes 2 to 5.5 and depths of 10 to 20 km during the period 1985-1997 were used to carry out the study. Velocities 6.01±0.15,6.57±0.13, 8.31±0.07 km/sec along the MCT, 6.0±0.1,6.54±0.13 and 8.24±0.14 km lsec along the MBF and 5.90±0.04,6.37±0.08 and 8.01±0.07 km/sec along the BPL for Pg, P* and Pn waves were obtained. The corresponding thicknesses of upper and lower crust are 28±1.6, 23.8±0.2 km for the MCT; 25.1±1.4, 23.8±0.2 km for the MBF and 21.5±1.5,23.8±0.2 km along the BPL (Fig. 2). A 6.5 krn thickening of upper crust from Assam towards Arunachal Himalaya is visualised.
Keywords
Travel Time, Crustal Structure, Main Boundary Fault, Main Central Thrust, Brahmaputra Lineament, Himalaya, Arunachal, Assam.
