Estimates of motion and strain rates across active faults in the frontal part of eastern Himalayas in North Bengal from GPS measurements

Abstract

Within the 2500 km stretch of the Himalayas, a narrow window between longitudes 88.185 E and 88.936 E in the frontal Himalayas in North Bengal, crisscrossed by several active fault traces, presents an interesting region for crustal deformation study. We have estimated velocities of 8 GPS stations located in this area and the accumulating strain rate by two different methods. A total shortening of 11.1 ± 1.5 mm yr)1 is occurring across a set of four E–W running faults: Gorubathan, Matiali, Chalsa and Baradighi. The strain rate becomes higher in the NE part of the network, reaching )(0.25 ± 0.12) lstrain yr)1 with azimuth 21 . A statistically significant extension of 10.9 ± 1.6 mm yr)1 is estimated across the Gish transverse fault with a maximum strain rate of 0.36 ± 0.08 lstrain yr)1 with azimuth 103 . The accumulating strain will be probably released through future earthquakes.