Stress pattern in two seismogenic sources in Nepal-Himalaya and its vicinity |
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| Authors: | Harihar Paudyal H N Singh Daya Shanker V P Singh |
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| Institution: | (1) Department of Geophysics, Banaras Hindu University, Varanasi, India;(2) Department of Earthquake Engineering, Indian Institute of Technology Roorkee, Roorkee, Uttaranchal, India;(3) Department of Physics, Birendra Multiple Campus, Tribhuvan University, Tribhuvan, Nepal |
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| Abstract: | The composite stereographic projection of orientations of the compression and tension axes using thirty-nine fault-plane solutions
of earthquakes from two active seismogenic sources of Nepal and adjoining areas were examined and the nature of stress pattern
and their influence on tectonics in the region have been studied. The seismogenic source located in Eastern Nepal region,
which has been the site of 1934 Bihar-Nepal great earthquake of M 8.4, is presently experiencing N-S to NE-SW directed compressive stresses. The inferred pattern of compression axes in Western
Nepal region suggests a shallow compressive stress, dipping N-S to NE-SW. Approximately similar nature of the stress regime
is observed in Western and Eastern regions of Nepal, separated by nearly 700 km; it shows N-S to NNE-SSW direction of compression
and underthrusting of the Indian Plate beneath the Himalaya at a shallow angle.
Present study indicates that the stress is being released along the strikes of some of the transverse faults present in the
region since the compressive stress exerted by the northward movement of the Indian Plate is approximately perpendicular to
the Himalayan collision belt. Unilateral stress pattern generated by the northward movement of the Indian Plate in the central
part of the Himalaya reveals that the present day collision occurs roughly perpendicular to the local strike of the Himalaya. |
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| Keywords: | Central Himalaya seismogenic sources stress pattern fault-plane solution |
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