Tectonic evolution of early precambrian south indian shield (rocks) using remotely sensed data

The interpretation of satellite imagery of part of South India falling South of 15 degree North latitude shows that the regional anticlines, synclines, domes and basins of the Precambrian group of metamorphites are aligned in three major hill ranges/domains such as Chitra-durga domain in the north, the Mangalore-Ootacamund-Bangalore domain in the centre and the Cochin-Cape Comorin-Madurai-Chittoor domain in the south. These hills are crescent shaped with their axes of elongation oriented in NNW-SSE direction. The lineaments with ENE-WSW, NE-SW/WNW-ESE and NNW-SSE azimuthal frequencies respectively exhibit extensional, shear and release geometries. Such deformational fabric shows that the tectonic evolution of South India was controlled by two major compressive forces, the first one aligned in N-S direction and the second in ENE-WSW direction.     

Geoinformatic Modeling of Groundwater Resource Mapping of Shear Zone Regions- A Case Study on Attur Valley,Tamil Nadu,India

The general tendency of mapping groundwater resource using remote sensing and Geographic Information System (GIS) techniques involve assigning higher weightage to geomorphology. But this cannot be used as a thumb rule everywhere, especially an area where many ductile and brittle zones are prevalent. The influence of texture and structure of sheared rocks might play a control over retaining and permitting groundwater to flow. Attur valley is characterized by the presence of many shear zones and faults and hence the rocks are highly fissile within the shear zones. The present study tries to establish a new ranking and weightage scheme and hence a new spatial model for groundwater resource mapping in shear zone area like Attur Valley. This spatial model can be verified with field data such as water level data, pump test and resistivity data.     

Widespread earth tremors in parts of Central Tamil Nadu on 12th August 2011 and its significance

The southern part of the Indian Peninsular has started witnessing fast recurring seismicities and earth tremors with the magnitude of 3–5 in the recent years. In this context, the earthquake occurred, with a magnitude of 3.5, east of Ariyalur, Central Tamil Nadu, on 12^th August, 2011 is significant. It is because, followed by the earthquake, tremors were felt in over 35–40 villages in an area of 8000 sq km along with the development of cracks and dislocations in buildings in several places. The remote sensing observations showed that while the Ariyalur epicenter is in the eastern Tertiary formations, the tremor felt villages lie in the western crystalline formations. Again the correlation of remote sensing based lineaments with Ariyalur earthquake, the related tremors and also a few past seismic events of the area showed that these epicenters mostly lie along NE-SW lineaments. The tremors related to Ariyalur event were also felt mostly in villages located again in the vicinity of NE-SW lineaments. The lineaments appear to be post collision tectonic grains related to the still on going northerly compressive force due to which only the Indian plate is buckling and fracturing now. Hence the 12^th August, 2011 seismic event of Ariyalur cannot be taken as an isolated phenomenon and appears to be related to the Indian plate deformation as a whole. So it calls for in depth studies in the context of fast relapsing seismicities in peninsular India.     

Geomatics Based Analysis of Predicted Sea Level Rise and its Impacts in Parts of Tamil Nadu Coast,India

The coastal zones around the world are very densely populated and hence heavily packed with related infrastructures. So, the territorial nations have obvious apprehensions against the IPCC SRES (Intergovernmental Panel on Climate Change, Special Report on Emission Scenario) predicted sea level rise, as it would cause flooding of the low lying coasts and also other related chains of environmental endangers. This has driven these nations to initiate research studies in multiple directions for scientifically evaluating the phenomenon and impacts of sea level rise using all possible technologies including the Geomatics which possesses unique credentials in geosystem mapping. But certain advanced virtues available with Geomatics technology are yet to be capitalized deservingly in this. In addition, almost all the earlier studies have focused only on the impacts of sea level rise (SLR) and not on the predicted shift of high tide line (HTL) and the related inter tidal activities, which would cause a series of environmental disaster. Hence, the present research study was undertaken in a test site of 750 km² in central Tamil Nadu coast to visualize the areas prone to submergence due to predicted SLR and areas prone to environmental disasters/degradation viz. erosion, deposition, salination of agricultural lands, pollution of aquifers, etc. due to predicted shift of HTL, using digital elevation models derived from SRTM data (Shuttle Radar Topographic Mission), geomorphology and land use/cover maps interpreted using IRS P6 LISS IV satellite data. The paper narrates the certain newer concepts and methodologies adopted in the study and the results.     

Flood 2018 and the status of reservoir-induced seismicity in Kerala,India

Natural Hazards - Floods in India, which were once mostly confined to southern part of the Himalayan region, have now started spreading over to many regions of India, including the urban...