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Stress Distribution in the Western India-Eurasia Collision Zone: its Kinematics and Seismotectonic implications.
  • R. Arun Prasath,
  • Brijesh Bansal,
  • MITHILA VERMA
R. Arun Prasath
Ministry of Earth Sciences, Ministry of Earth Sciences

Corresponding Author:[email protected]

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Brijesh Bansal
Unknown, Unknown
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MITHILA VERMA
GEOSCIENCE DIVISION, MINISTRY OF EARTH SCIENCES, GEOSCIENCE DIVISION, MINISTRY OF EARTH SCIENCES
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Abstract

To evaluate stress distribution of the western India-Eurasia collision zone (IECZ), an iterative joint stress inversion technique has been applied to a declustered catalogue of 324 focal mechanisms for the first time. The results are then used to understand fault kinematics, seismogenesis and seismotectonics of the region. The inversion results reveal an NNE-SSW trending principal stress (σ1) with compression for the Himalayan seismic belt and an NNE-SSW trending σ1 with strike-slip stress regime for the Karakoram-Tibet, consistent with plate motion of the Indian plate. Within the Himalaya region, the western Himalaya (75°-77°; E) exhibits arc-oblique compression (NE-SW) in contrast to arc-normal compression (NNE-SSW) in central Himalaya beyond 77°E; consistent with GPS vectors. Stress field for the aftershock sequence of the 2005 Kashmir earthquake in the Hazara Syntaxis region show dissimilarity with its surrounding regions (Pamir, Nanga Parbat, Hindukush, etc.), however, exhibits similarity with that of the Central Himalaya; therefore, we suggest this earthquake be Himalayan-type. Within the Karakoram-Tibet region, the Karakoram fault exhibits transpression oriented towards NNE-SSW, while the transverse structure i.e., the Kaurik Chango rift (KCR) located south of the Karakoram Fault shows transtensional motion with N-S oriented principal stress. The stress ratio in the western IECZ largely varies between 0.07 and 0.9, thus supports the significant role of the intermediate stress axis (σ2) in the areas of low-stress ratios. Besides, the low-stress ratios for Hazara Syntaxis, Karakoram-Tibet and KCR reveal the role of local structural variability and multiple tectonic forces suggesting heterogeneous stress field in the western IECZ.
Jun 2022Published in Journal of Asian Earth Sciences volume 230 on pages 105208. 10.1016/j.jseaes.2022.105208