Understanding the Tectonic Behaviour of the Shillong Plateau, India using Remote Sensing Data

Abstract

Shillong Plateau in India is tectonically and geologically interesting entity in the subducted front of Indian Plate below Burmese Plate to the southeast and Tibetan Plate to the north and associated with thrusts and shears along the plate boundaries. Horse-tail geometry in the foothills of the Arunachal Himalaya, east of Jia Bhareli river, associated with south-convex foothill ranges in the eastern Himalaya and exactly similar structural geometry in the eastern part of Shillong Plateau in Meghalaya seems to develop due to resistance received by the plateau in its eastward journey. Wide separation of Karbi Anglong Plateau and Shillong Plateau to the southeast as compared to northwestern part defines the shape of Kopili graben. Low seismic activity in southeastern part of Shillong Plateau might be related to stress released field generated by its clockwise rotation. Satellite derived images and digital elevation data from Landsat ETM+ and SRTM data shows that the central part of Shillong Plateau possesses young topography with strong structural fabrics along with relatively high topography aligning NE-SW following Kolkota-Pabna-Mymansingh High and if extended passes through western part of Arunachal Pradesh in eastern Himalayas. This alignment has been observed in Precambrian gneissic complex west of the Proterozoic intracratonic Shillong Basin. The epicentral plot for the period 1918 to 2009 shows their high concentration within the Shillong Plateau aligning along this trend. The active geodynamics of Shillong Plateau is reflected in its seismic activity pattern in relation with the structural fabrics, northward migration of the Brahmaputra in the north front of the Plateau and by shrinking pattern of Chandubi Lake in the Kulsi river catchment, a north-flowing tributary of the Brahmaputra in the north-central part of the plateau.

Ascertaining the Neotectonic Activities in the Southern Part of Shillong Plateau through Geomorphic Parameters and Remote Sensing Data

“…THE Shillong Plateau is considered as a detached block of a subducted wedge of the peninsular India in front of the Indian and Tibetan continental mass 1 . It is bounded by the Dauki Fault in the south, the Himalayan Orogenic Belt in the north, the Kopili Fault in the east and the Dhubri Fault in the west (Figure 1).…”

“…Beyond the Dhubri Fault lies the Bengal Graben further to the south [2][3][4] . The Shillong Plateau is considered as a tectonically active popup continental block 1,[5][6][7][8] . The existence of the proposed Oldham Fault 7 (Figure 1) representing the northern margin of the pop-up tectonics is, however, debatable 8 .…”

Seismic hazard assessment in the Jia Bhareli river catchment in eastern Himalaya from SRTM-derived basin parameters, India

“…The geological evidences of the ruptures associated with the earthquakes do not extend to the surface, which is a common characteristic even for the high-magnitude earthquakes [ 8.0 M of the Himalayas, and 'there are thus no geological constraints of recent ruptures' (Bilham et al 2001). We belief, the fault is extending further southsouthwest to the Shillong Plateau west of which a belt of epicenters exist (Duarah and Phukan 2011). East of this fault, the fan-shaped structure with smooth mountain front convex toward the Brahmaputra valley, containing well-defined trend line is giving evidence of strain built-up process in the region (Das 2004).…”

Lithological control on the geomorphic evolution of the Shillong Plateau in Northeast India

“…When disagreement occurs, we refer to the Geological Survey of India's District Resource Map series by Mukherjee et al, (2012aMukherjee et al, ( , 2012bMukherjee et al, ( , 2013aMukherjee et al, ( , 2013bMukherjee et al, ( , 2013cMukherjee et al, ( , 2014 which is based on field mapping. Linear geological features are exploited by rivers throughout the plateau (Gupta and Sen, 1988;Das et al, 1995;Biswas and Grasemann, 2005;Yin et al, 2010;Duarah and Phukan, 2011) and evidence heterogeneities in lithological erodibility. However, while significant plan-form control on flow routing is exerted by these features, comparison of linear channels with their non-linear neighbours reveals limited elevation differences in the south and central plateau region, suggesting that the extent of perturbations in long profile form driven by these linear features is limited in the context of the large vertical scales (> hundreds of meters) considered in this analysis.…”