Current Science

S. Das Sharma ¹, D. S. Ramesh ²

Affiliations
1 CSIR-National Geophysical Research Institute, Uppal Road, Hyderabad 500 007, IN
2 Indian Institute of Geomagnetism, Navi Mumbai 410 218, IN

Abstract

No Abstract.

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K. M. Sreejith ¹, P. S. Sunil ², Ritesh Agrawal ¹, D. S. Ramesh ², A. S. Rajawat ¹

Affiliations
1 Geosciences Division, Space Applications Centre (ISRO), Ahmedabad 380 015, IN
2 Indian Institute of Geomagnetism (DST), Navi Mumbai 410 218, IN

Abstract

We present InSAR observations of the co-seismic deformation caused by the Mw 7.8 Gorkha, Nepal earthquake. Analysis of Sentinel-1 data revealed about 100 x 100 sq. km surface deformation with ~1 m upliftment near Kathmandu, and ~0.8 m subsidence towards north along the line of sight of the satellite. The maximum deformation is observed about 40 km east-southeast of the epicentre, suggesting eastward propagation of the rupture. Elastic dislocation modelling revealed that the overall rupture occurred on a 170 km long, 60 km wide fault along the strike (286°) and dipping north (dip = 15°) with large amount of slip (4.5 m) confined to the centre (95 x 22 sq. km) and less slip (0.25 m) on the surrounding part of the fault plane. The corresponding moment magnitude is M_w 7.75. The area, depth and dip of the modelled fault plane are fairly consistent and overlap with the location of mid-crustal ramp in the Main Himalayan Thrust. We infer that the earthquake was possibly caused by the release of inter-seismic strain energy accumulated in the environs of mid-crustal ramp due to plate boundary forces.

Keywords

Co-Seismic Deformation, Gorkha, Nepal Earthquake, Synthetic Aperture Radar Interferometry, Source Model.

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R. Divya Bharathi ¹, M. Subrahmanyam ¹, D. S. Ramesh ², S. Rajendran ³

Affiliations
1 Department of Geophysics, Andhra University, Visakhapatnam 530 003, IN
2 Indian Institute of Geomagnetism, Kalamboli Highway, New Panvel, New Mumbai 410 218, IN
3 Department of Earth Sciences, Kerala University of Fisheries and Ocean Studies, Panangad, Cochin 682 506, IN

Abstract

Nine total magnetic profiles in the S–N direction of the Central Indian Ocean (CIO) have been interpreted with spectral and Werner deconvolution techniques to obtain approximate depths to shallow (magnetic basement) and deeper (Curie isotherm) interfaces of the oceanic crust. From these preliminary depths, tentative crustal models for all these nine profiles are prepared. These tentative models of the area show varying thickness of the oceanic crust, supporting the deformation history. It is inferred from these tentative models that deformation extends beyond the zone identified south of 8°S latitude. There is good agreement between the spectral and Werner deconvolution depths.

Keywords

Deformation Zone, Deconvolution Techniques, Magnetic Anomaly, Oceanic Crust, Tentative Model.

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