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Volume 17 No.4 October 2013


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Past and present day plate tectonics – Suggested solutions to understand the genesis and mechanism of 2005 Kashmir and 1993 Latur earthquakes

D.C. Mishra

CSIR-National Geophysical Research Institute, Hyderabad-500 007, India
E-mail: dcm_ngri@yahoo.co.in

Plate tectonics has been one of the most fascinating theories developed during the last century. Its importance lies in its capacity to explain most of the features and observations related to earth both in the present and the past. It’s important stages include collision of two plates and subduction of one under the other and gamut of activities that arise from it, such as earthquakes, volcanoes etc. Present day model of the collision of the Indian and the Asian plates is described along a profile across the western syntaxis and plausible causes for the Kashmir earthquake of 2005 are discussed. Kashmir earthquake of magnitude 7.6 has been one of the most devastating earthquakes located in the well known Indus Kohistan Seismic Zone (IKSZ) of the Western Syntaxis. It is caused by the interaction of the Main Boundary Thrust with a density discontinuity between the upper and the lower crusts, in a fluid filled zone. This model also suggests that the sub-ducted lithosphere of the Indian plate has a thickness of 140-160 km, while that of the Asian plate ranges between 140-250 km. The thickest crust of ~65-70 km is found under the Pamir ranges of the Asian plate. There have been tectonic activities, similar to plate tectonics during Proterozoic period. This is noticed from the present day structure along the Satpura Mobile Belt (SMB). In light of this, causes for the Latur earthquake of 1993 have been discussed. Intra-plate Latur earthquake of magnitude 6.3 might have been related to the remnants of the sub-ducted slab of the Proterozoic Satpura orogeny and associated thrust. The sub-ducted slab of this orogeny appears to lie presently under this region in the lithospheric mantle, delineated based on high conductivity and low density fluid filled zone. Any movement of this sub-ducted slab would generate stress leading to seismic activity in this area. Such a movement has probably been responsible for 1963 Latur earthquake activity.


Studies on the trend and chaotic behaviour of Tamil Nadu rainfall

P. Indira1, S. Stephen Rajkumar Inbanathan2

1Research and Development Centre, Bharathiar University, Coimbatore, India
2Post-Graduate Research Department, The American College, Madurai-625 002, India
Email: indiraindhu2006@gmail.com

This study is aimed at in finding the trend or nonlinearity that may exist in the rainfall pattern of the State of Tamil Nadu. Based on the observed rainfall data for a period of 111 years (1901-2011), a trend analysis with Hurst exponent and non-linearity analysis with Lyapunov exponent is employed. The interpretation of the Hurst exponent of Tamil Nadu rainfall indicates that the Southwest Monsoon rainfall shows a persistent behaviour, whereas the annual rainfall shows an anti-persistence behaviour. The Northeast Monsoon, which is the most important season for the State of Tamil Nadu shows a randomness or non-linearity in its value. The non-linearity in the Northeast Monsoon has been verified through Lyapunov Exponent. The Northeast Monsoon shows a largest positive Lyapunov exponent value than the Southwest and Annual rainfall. This indicates that the Northeast Monsoon of Tamil Nadu is chaotic. The chaotic nature of the Northeast Monsoon is also verified using surrogate data method.


Magnetic properties of dolerite dykes and lamprophyre sills from Jharia coal fields, Damodar valley basin, India
Ramesh K. Nishad1*, Anup K. Sinha1, V. Kumaravel1, 2, S.K. Patil1
1Dr. K.S. Krishnan Geomagnetic Research Laboratory, Allahabad–221 505
2Geological Survey of India, Nagpur–440 006
*E-mail: rknishad@iigs.iigm.res.in

The Gondwana (Early Permian to Early Cretaceous) basins of eastern India have been intruded by ultramafic-ultrapotassic and mafic (dolerite) dykes. Total 35 samples from 7 sites of dolerite dykes and lamprophyre sills have been collected from the Jharia coal field of the Damodar valley basin for rock magnetic studies. The investigations mainly comprise of magnetic susceptibility measurement, isothermal remanent magnetization (IRM), Lowrie-Fuller (L-F) test and thermomagnetic (K-T) experiment. The natural remanent magnetization (NRM) intensities measured on 450 specimens of dolerite dykes and lamprophyre sills show a mean value of 4.06 A/m and 0.003 A/m. Magnetic susceptibility values indicate mean values of 30.93 x 10-3 and 0.41 x 10-3 SI units. The Koenigsberger ratio (Qn) value of dykes and sills show mean value of 3.47 and 0.19, respectively. Rock magnetic studies indicate that titano-magnetite/ magnetite of pseudo single domain (PSD)/ single domain (SD) type are the main magnetic minerals present in the studied samples of the Damodar valley basin.

Petrophysical and mechanical properties of cretaceous sedimentary rocks of Cauvery basin, Eastern Continental Margin of India
Rima Chatterjee1, K. Manoharan2, and Manoj Mukhopadhyay3
1Department of Applied Geophysics, Indian School of Mines, Dhanbad-826 004, India
2Great Eastern Energy Corporation Limited, Mannargudi CBM Project, Thanjavur, Tamil Nadu
3Department of Geology & Geophysics, King Saud University, P.O. Box 2455, Riyadh 11451, Kingdom of Saudi Arabia
1E-mail: rima_c_99@yahoo.com

The Cauvery Basin (CB) is one of the largest petroliferous basins developed at the Eastern Continental Margin of India (ECMI) where the sediments thicken to as much as 8,000 m. Hydrocarbon bearing formations in the basin belong to Cretaceous age. Both microscopic and macroscopic heterogeneities for the cored rocks corresponding to depths of 2169–2669 m are studied for their mechanical and petrophysical properties. The petrophysical and mechanical properties of the samples tested have been correlated with a fair degree of fit. Further, it is observed that the Vp/Vs, the ratio of compressional wave velocity (Vp) to shear wave velocity (Vs) has been found to decrease with the increase of effective porosity of the core samples. The best fit regression may be used for estimation of porosity from the Vp/Vs values as well as from the density values for the Cretaceous sediments of Cauvery basin.

Feasibility of forewarning high lightning incidence by electric field measurements
V. Anil Kumar1, R. Vishnu2, V.N. Subi Symon3, S. Murali Das3 and G. Mohan Kumar3
1Indian Institute of Tropical Meteorology, Pune, India.
2PG Dept. of Physics, Sree Krishna College, Guruvayur, India.
3Centre for Earth Science Studies, Thiruvananthapuram-31, India.
1E mail: anilchry@gmail.com

In India, the Kerala State has relatively higher level of lightning occurrences. Spatial and temporal distribution of lightning incidences/ accidents in Kerala shows that nearly 62% of the accidents happen during April, May (summer and onset of monsoon) and October, November (north-east monsoon). The lightning events mostly occur in the evening hours. The formation and build-up of thunder-clouds seems to maximise due to tropical land masses and orography of the Western Ghats. Our study is an attempt to evaluate the feasibility of providing an electronic warning system, which utilizes a radioactive potential equaliser (RAPE) sensor. Details of the indigenously fabricated sensor used and preliminary results are presented and discussed.

Sustainable Development, Ethics, Environmental Ethics and Geo-ethics: A Perception
P.R. Reddy
Scientist-G (Ret.), CSIR-NGRI, Hyderabad-500 007
E-mail: parvatarreddy@gmail.com

It is evident from recent upsurge of Natural Hazards that we need to take appropriate measures, following ethical norms, to ensure sustainable development of quality of life and safety of the environment. It is pointed out that Man`s selfish and over ambitious acts have degraded the environment and to arrest further degradation all the stake holders have to learn to be positive in word and deed, following ethical norms. To ensure safety of our environment and there by enhance quality of life we need to make use of environmental ethics and Geoethics, in a concerted manner. .

Monsoon season soil wetness over India - ENSO and LNSO Events
A.A.L.N. Sarma1 and V. Vizaya Bhaskar
1Andhra University, Visakhapatnam
Door # 1-114-11, Plot # 40, Sector 12, MVP Colony, Visakhapatnam–530 017 (A.P)
Meteorological Office, Shivaji Nagar, Pune
E-mail: aalnsarma_met@rediffmail.com, vvvbhaskar@yahoo.com

The climatic soil wetness pattern over India, during monsoon and its course is investigated using the modified Penman PE in the revised water balance model. The variations in atmospheric circulation patterns that are modulated by the ENSO and LNSO signals can be traced from land surface processes, for soil wetness. Anomalies in monsoon season mean soil wetness for the events of ENSO 1982, 1987 and LNSO 1988 is discussed. Synoptic effects that restrained and complemented from ENSO and LNSO signals that weakened and strengthened the monsoon performance, respectively ultimately resulted in depleting and enriching soil wetness, respectively over the zones of their influence.
The short term climate signal of ENSO or LNSO in depleting or enriching the soil wetness in terms of area and percentage is in accordance with the advance or retrieval of southwest monsoon along with the agricultural land use. Negative anomalies dominated in terms of area and magnitude compared to positive anomalies in soil wetness, during the ENSO years of 1982 and 1987, while the LNSO event of 1988 ,even though affected some parts of the country by depleting soil wetness, recharged long swaths of the landscape with positive anomalies. The total sown area and overall agricultural production of major crops over the country as a whole for the kharif season has decreased compared to ENSO years 1982 and 1987. But the agricultural yields improved in the subsequent LNSO year of 1988. Majority of the States and Union Territories recorded a decrease in sown area. The overall agricultural production was below normal in the kharif season due to ENSO episodes, compared to the kharif season of 1988.

Geothermal Energy Resources in Uttarakhand, India
Vijay P Dimri
CSIR-National Geophysical Research Institute, Hyderabad-500 007
Email: dimrivp@yahoo.com

There are about 50 hot springs in Uttarakhand. The surface temperature of water of hot springs of Uttarakhand varies from 25°C-90°C. Application of high temperature can be used for 1) heating the houses and 2) generating the electricity depending on the temperature. Morethan 140°C is required to move the turbine to generate the electricity. Geophysical methods are suitable to find the temperature as a function of depth. Geophysical studies in Tapoban area have been conducted by CSIR-NGRI and it is shown that this area is potential area for generating electricity. For higher altitude area in Uttarakhand the heat pumps are recommended to warm the houses during the winter season.

Identification of groundwater potential locations using high-resolution satellite data in a densely populated urban area of greater Hyderabad city, Andhra Pradesh, India
K. Seshadri and P. Chandrasekhar
Hydrogeology Group, RSA-A, National Remote Sensing Centre (NRSC),
Indian Space Research Organization (ISRO), Dept of Space (DOS), Government of India, Hyderabad–500 037 (A.P)
*E-mail: seshadri.nrsc@gmail.com

Selection of new bore well sites for augmenting drinking water supply in urban areas is a challenging task because of rapid changes in topography consequent to changes in land use pattern. The natural topography for understanding the recharge, transition and discharge of groundwater resource is to be deduced, besides understanding the lithology, landforms and the geological structures. Though the geophysical surveys such as ‘electrical resistivity’ are the best techniques for this type of investigations, they have constraints due to the extensive urbanization of the area. Hence, high-resolution Indian Remote Sensing (IRS) satellite data sets, namely CARTOSAT-1 and LISS-IV and the hybrid image generated by merging the above two, were interpreted over a densely populated area of northern part of Hyderabad city. The landforms such as the pediments and the shallow weathered pediplains and all the geological fractures passing through the area were interpreted. Inventory of existing bore wells was carried out and correlated with the geological parameters observed on the ground as well as those interpreted using satellite data. The Digital Elevation Model (DEM) generated using Aster data onboard Terra satellite of NASA having a spatial resolution of 30 m was used for further confirmation of the topography of the area, in a regional perspective. Airborne magnetic anomalies were also observed to be correlating well with that of the above interpretation. Hence, by integrating all the above geological information, three possible potential locations on priority basis were identified and recommended for drilling. Subsequently, a bore well was drilled on the second priority location based on the drilling convenience and was successful.

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Copyright - 2004
Indian Geophysical Union, Hyderabad 500 007 India, 
For problems or questions regarding this web contact  IGU Email]
. Designed by Artworks