![]() We will combine our results with previous studies of well-constrained source mechanisms and GPS velocity field to unravel the kinematics of active deformation across northeast India. We conjecture that the strike-slip faults in the Bengal Basin are reactivated passive continental margin rift faults with left-lateral motion. Our results of earthquake source parameters, directivity effects, and source mechanisms reveal dextral strike-slip faults in the KFZ and the western Brahmaputra Valley. In order to understand the role of these strike-slip faults in accommodating the GPS derived convergence across northeast India, we study the source mechanism of recent earthquakes using teleseismic (for earthquakes with Mw>5) and local (4.0faulting in the KFZ also extends northwards beneath the Eastern Himalaya and southeastward beneath the Naga fold-thrust belt. The Tintina fault system is a major right-lateral strike-slip fault and extends for more than. However, south-west of the plate boundaries, the middle-to-lower crust deforms by strike-slip faulting in the Kopilli Fault Zone (KFZ) upper-to-mid crustal strike-slip faulting along the western Brahmaputra Valley and lower crustal strike-slip faulting beneath the Bengal Basin. Previous studies of spatial distribution and source mechanism of earthquakes have shown that the N20E convergence between India and Tibet is partitioned into N-S underthrusting and E-W subduction of the Indian plate beneath the Himalaya and Burma micro-plate, respectively. This plate boundary system is different from the central Nepal Himalaya, due to oblique convergence across two orthogonal plate boundaries, resulting in a zone of distributed deformation both within and away from the plate boundary. ![]() right-lateral slip on this fault, and 3.8 1.4 mm/yr of. Comparison of the Kuh-e-Hori transpression zone, between the Esmail-abad and West Neh left-stepping right-lateral strike-slip fault segments in SE Iran, with the modelling results shows strong similarities with the neutral step configuration.Northeast India is sandwiched between the seismically active plate boundaries of the Eastern Himalaya to the north and the Indo-Burman subduction zone to the east. faults result from brittle deformation, and they clearly are important in the deformation that. The modelled mean stress pattern shows a similar pattern to that of the contractional steps, and decrease and increase in underlapping and overlapping fault steps, respectively. ![]() A lozenge-(for under-lapping steps), rhomboidal-(for neutral steps), and sigmoidal-shaped (for overlapping steps) trans-pression zone developed between the two segments. Interaction between the two fault segments perturbs the stress field and reflects the heterogeneous nature of deformation. These flow patterns are related to friction effects and different shear deformation, from pure shear outside of the fault steps toward simple shear along the fault segments. For overlapping faults, the s 1 trajectories within the transpression zone deflects significantly forming a sigmoidal pattern, which is created by two rotational flow patterns close to the fault tips. For neutral and overlapping fault steps, there is a contractional linking damage zone between the fault segments. ![]() The orientations of the local s 1 (the maximum compressive stress) and s 3 (the minimum compressive stress) directions strongly depend on the structural position within the transpression zone. ![]() The numerical results indicate that at the onset of deformation, displacement vectors are oblique to the regional compression direction (20e90). Three representative fault segment interactions are modelled: underlapping, neutral, and overlapping. Fault: A break in the Earth in which the rocks on either side of the break have been displaced (vertically and/or horizontally) relative to each other (see pictures below). Two-dimensional finite-element modelling of elastic Newtonian rheology is used to compute stress distribution and strain localization patterns in a transpression zone between two pre-existing right-stepping, left-lateral strike-slip fault segments. Joint: A break in a rock (crack) in which there is no relative movement of either side across the break. ![]()
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