Role of Intraplate Strike-Slip Earthquakes in Accommodating Convergence Across the Eastern Himalayan Plate Boundary System
North-East India, at the eastern extremity of the Himalaya, is one of the most rapidly deforming intraplate regions. The tectonics of this region is shaped by oblique convergence between two nearly perpendicular plate boundaries of the Eastern Himalaya and the Indo-Burman convergence zone. This regi...
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GeoScienceWorld
2024-12-01
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| Series: | Lithosphere |
| Online Access: | https://pubs.geoscienceworld.org/gsw/lithosphere/article-pdf/doi/10.2113/2024/lithosphere_2024_189/7085243/lithosphere_2024_189.pdf |
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| author | Dibyajyoti Chaudhuri Rupak Banerjee Ajay Kumar Shubham Sharma Supriyo Mitra |
| author_facet | Dibyajyoti Chaudhuri Rupak Banerjee Ajay Kumar Shubham Sharma Supriyo Mitra |
| author_sort | Dibyajyoti Chaudhuri |
| collection | DOAJ |
| description | North-East India, at the eastern extremity of the Himalaya, is one of the most rapidly deforming intraplate regions. The tectonics of this region is shaped by oblique convergence between two nearly perpendicular plate boundaries of the Eastern Himalaya and the Indo-Burman convergence zone. This region of distributed deformation is associated with intraplate strike-slip and oblique-slip earthquakes. We model the source mechanisms of six recent moderate-to-strong intraplate earthquakes (5.0≤ Mw ≤6.7) using teleseismic P- and SH-waveform inversion and use source directivity and rupture back-projection, for the largest event, to isolate the fault plane. We combine these mechanisms with previous earthquake source studies, GPS-geodetic-velocity vectors, and GPS-derived strain-rate field, to build a kinematic model. Majority of the earthquakes have strike-slip to oblique-slip (thrust) motion and originate in the middle-to-lower crust. These reveal that the entire NE-Indian crust is seismogenic. The oblique-thrust earthquakes occur due to high in-plane compressive stresses in the flexed Indian Plate. The region north of the Dawki Fault, in the vicinity of the Kopili and Dhubri-Chungthang Fault Zones, deforms through dextral strike-slip faulting and anticlockwise rotation of blocks along NW-SE trending transverse structures. The transitional crust of the Bengal Basin has several NE-SW trending paleo-rifts which are reactivated as sinistral strike-slip faults and the intervening blocks undergo clockwise rotation. The oblique convergence between the Indian and Eurasian Plates is partitioned into dextral and sinistral strike-slip motions across NE-India. The GPS velocity vectors and the strain-rate field indicate that the region north of the Dawki Fault has strong coupling between the surface deformation and the earthquake faulting. However, in the region south of the Dawki Fault, the coupling is weaker. The strike-slip earthquakes beneath Indo-Burma probably occur due to a complex interplay between the trench-normal slab-pull forces and lateral-shear forces set up by the strike-parallel components of the interplate-coupling resistance and the mantle-drag forces. |
| format | Article |
| id | doaj-art-727ddd8bfabb40959f58899e4206d370 |
| institution | Kabale University |
| issn | 1941-8264 1947-4253 |
| language | English |
| publishDate | 2024-12-01 |
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| series | Lithosphere |
| spelling | doaj-art-727ddd8bfabb40959f58899e4206d3702025-01-22T09:28:57ZengGeoScienceWorldLithosphere1941-82641947-42532024-12-012024Special 1510.2113/2024/lithosphere_2024_189Role of Intraplate Strike-Slip Earthquakes in Accommodating Convergence Across the Eastern Himalayan Plate Boundary SystemDibyajyoti Chaudhuri0https://orcid.org/0009-0001-5972-8923Rupak Banerjee1https://orcid.org/0009-0003-8885-2194Ajay Kumar2https://orcid.org/0000-0002-2669-355XShubham Sharma3https://orcid.org/0000-0003-2308-2347Supriyo Mitra4https://orcid.org/0000-0002-5252-3757Department of Earth Sciences, Indian Institute of Science Education and Research Kolkata, Mohanpur, West Bengal, IndiaDepartment of Earth Sciences, Indian Institute of Science Education and Research Kolkata, Mohanpur, West Bengal, IndiaDepartment of Earth and Climate Science, Indian Institute of Science Education and Research, Pune, Maharashtra, IndiaDepartment of Earth Sciences, Indian Institute of Science Education and Research Kolkata, Mohanpur, West Bengal, IndiaDepartment of Earth Sciences, Indian Institute of Science Education and Research Kolkata, Mohanpur, West Bengal, IndiaNorth-East India, at the eastern extremity of the Himalaya, is one of the most rapidly deforming intraplate regions. The tectonics of this region is shaped by oblique convergence between two nearly perpendicular plate boundaries of the Eastern Himalaya and the Indo-Burman convergence zone. This region of distributed deformation is associated with intraplate strike-slip and oblique-slip earthquakes. We model the source mechanisms of six recent moderate-to-strong intraplate earthquakes (5.0≤ Mw ≤6.7) using teleseismic P- and SH-waveform inversion and use source directivity and rupture back-projection, for the largest event, to isolate the fault plane. We combine these mechanisms with previous earthquake source studies, GPS-geodetic-velocity vectors, and GPS-derived strain-rate field, to build a kinematic model. Majority of the earthquakes have strike-slip to oblique-slip (thrust) motion and originate in the middle-to-lower crust. These reveal that the entire NE-Indian crust is seismogenic. The oblique-thrust earthquakes occur due to high in-plane compressive stresses in the flexed Indian Plate. The region north of the Dawki Fault, in the vicinity of the Kopili and Dhubri-Chungthang Fault Zones, deforms through dextral strike-slip faulting and anticlockwise rotation of blocks along NW-SE trending transverse structures. The transitional crust of the Bengal Basin has several NE-SW trending paleo-rifts which are reactivated as sinistral strike-slip faults and the intervening blocks undergo clockwise rotation. The oblique convergence between the Indian and Eurasian Plates is partitioned into dextral and sinistral strike-slip motions across NE-India. The GPS velocity vectors and the strain-rate field indicate that the region north of the Dawki Fault has strong coupling between the surface deformation and the earthquake faulting. However, in the region south of the Dawki Fault, the coupling is weaker. The strike-slip earthquakes beneath Indo-Burma probably occur due to a complex interplay between the trench-normal slab-pull forces and lateral-shear forces set up by the strike-parallel components of the interplate-coupling resistance and the mantle-drag forces.https://pubs.geoscienceworld.org/gsw/lithosphere/article-pdf/doi/10.2113/2024/lithosphere_2024_189/7085243/lithosphere_2024_189.pdf |
| spellingShingle | Dibyajyoti Chaudhuri Rupak Banerjee Ajay Kumar Shubham Sharma Supriyo Mitra Role of Intraplate Strike-Slip Earthquakes in Accommodating Convergence Across the Eastern Himalayan Plate Boundary System Lithosphere |
| title | Role of Intraplate Strike-Slip Earthquakes in Accommodating Convergence Across the Eastern Himalayan Plate Boundary System |
| title_full | Role of Intraplate Strike-Slip Earthquakes in Accommodating Convergence Across the Eastern Himalayan Plate Boundary System |
| title_fullStr | Role of Intraplate Strike-Slip Earthquakes in Accommodating Convergence Across the Eastern Himalayan Plate Boundary System |
| title_full_unstemmed | Role of Intraplate Strike-Slip Earthquakes in Accommodating Convergence Across the Eastern Himalayan Plate Boundary System |
| title_short | Role of Intraplate Strike-Slip Earthquakes in Accommodating Convergence Across the Eastern Himalayan Plate Boundary System |
| title_sort | role of intraplate strike slip earthquakes in accommodating convergence across the eastern himalayan plate boundary system |
| url | https://pubs.geoscienceworld.org/gsw/lithosphere/article-pdf/doi/10.2113/2024/lithosphere_2024_189/7085243/lithosphere_2024_189.pdf |
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