[1] Images of the crust and mantle beneath northeast India obtained by 2D migration of $1000 broadband P-receiver functions clearly trace a northward dipping Moho from the Himalayan foredeep reaching depths up to 50 km further north beneath the Himalayan convergence zone. Also, these images reveal presence of largely coherent 410-km and 660-km discontinuities that conform to the IASP91 model. Marginal variations in the depth of the 410-km interface are observed, that appear region specific. The thickness of the mantle transition zone does not deviate significantly from a global average of $250 km. Interestingly, our results reveal consistent presence of a signal from an interface around 300 km. Origin of such a boundary, known as X-discontinuity and unrelated to the Lehmann discontinuity, is discussed. Possible presence of the X-discontinuity from the Indian region is reported here for the first time. Citation:
Teleseismic receiver functions from a ten station network deployed in northeast India region sampling the Shillong plateau, Mikir Hills, Himalayan foredeep and the Himalayan convergence zone, are analyzed to obtain the crustal structure in this seismically active but less studied region. The Shillong plateau and Mikir hills, away from the convergent margins, reveal remarkably simple crust with thickness (∼35 km) and Poisson's ratio (∼0.25), akin to the Indian shield values. A surprisingly thin crust for the uplifted Shillong plateau may be explained invoking presence of an uncompensated crust that popped up in response to tectonic forces. In contrast, crustal signatures from Assam valley suggest a thicker crust and higher Poisson's ratio with evidences for a dipping Moho. Predictably, the crust is much thicker and complicated in the eastern Himalaya further north, with values in excess of 50 km.
SUMMARY Lithospheric thickness is an important parameter to understand the nature of collision and subduction between the Indian and Asian tectonic plates. In this study, we apply the S receiver function technique to data from a network of broad‐band stations in the northeast India and Eastern Himalayan regions and image the geometry of Indian Plate collision. This analysis reveals clear S‐to‐p conversions from the Moho and Lithosphere‐‐Asthenosphere boundary (LAB) in the various tectonic units of the study region. The Indian lithosphere is found to be only 90 km thick beneath the Shillong plateau deepening to 135 km on either side suggestive of a lithospheric upwarp related to the plateau uplift. The lithosphere thickens northward, with values reaching ∼180 km beneath the Eastern Himalaya. The trend of the LAB north of the foredeep region indicates that the Indian Plate plunges beneath the Eastern Himalaya. The consistent northward‐dipping character of the Indian Plate suggests that the Indian Plate is traceable until it gets subducted beneath Tibet just south of Bangong suture zone. The deepening of the LAB and its correlation with the topographic elevation is in agreement with homogeneous thickening of the lithosphere in response to compressive forces due to the continental collision of India with Asia.
The Indian Tsunami Early Warning System situated at Indian National Center for Ocean Information Services, Hyderabad, India, monitors real-time earthquake activity throughout the Indian Ocean to evaluate potential tsunamigenic earthquakes. The functions of the Indian Tsunami Early Warning System earthquake monitoring system include detection, location and determination of the magnitude of potentially tsunamigenic earthquakes occurring in the Indian Ocean. The real-time seismic monitoring network comprises 17 broadband Indian seismic stations transmitting real-time earthquake data through VSAT communication to the central receiving stations located at the Indian Meteorological Department, New Delhi, and the Indian National Center for Ocean Information Services, Hyderabad, simultaneously for processing and interpretation. In addition to this, earthquake data from around 300 global seismic stations are also received at the Indian National Center for Ocean Information Services in near-real-time. Most of these data are provided by IRIS Global Seismographic Network and GEOFON Extended Virtual Network through Internet. The Indian National Center for Ocean Information Services uses SeisComP3 software for auto-location of earthquake parameters (location, magnitude, focal depth and origin time). All earthquakes of Mw >5.0 are auto-located within 5-10 minutes of the occurrence of the earthquake. Since its inception in October 2007 to date, the warning centre has monitored and reported 55 tsunamigenic earthquakes (under-sea and near coast earthquakes of magnitude ⩾6.5) in the Indian Ocean region. Comparison of the earthquake parameters (elapsed time, magnitude, focal depth and location) estimated by the Indian Tsunami Early Warning System with the US Geological Survey suggests that the Indian Tsunami Early Warning System is performing well and has achieved the target set up by the Intergovernmental Oceanographic Commission.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.