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Volume 18 No.1 January 2014

 

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Editorial


1
 

Gas-hydrates, A Major Energy Resource of India for the Next Generation

Kalachand Sain1 and Harsh K Gupta2

1CSIR-National Geophysical Research Institute, Uppal Road, Hyderabad - 500 007
2National Disaster Management Authority Bhawan, A-1, Safdarjung Enclave, New Delhi -110 029
Email: kalachandsain@yahoo.com; harshg123@gmail.com


ABSTRACT
Gas-hydrates are crystalline form of 99% methane and 1% water. They have attracted the attention of geo-scientific community due to their abundant occurrences in the outer continental margins and permafrost regions, and huge energy potential as a viable major energy resource of future. The bathymetry, seafloor temperature, total organic carbon content, sediment-thickness, rate of sedimentation, geothermal gradient imply that shallow sediments of Indian margin are good hosts for gas-hydrates. The methane within gas-hydrates has been prognosticated to be more than 1500 times of India's current natural gas reserve. If we produce only 10% from this gigantic treasure, it can meet India's overwhelming energy requirement for about 100 years. Thus, it was felt necessary to map the prospective zones of gas-hydrates and evaluate their resource potential to boost the exploitation program. We have prepared the theoretical map of gas-hydrates stability thickness along the Indian margin, at the base of which is observed an anomalous seismic reflector, known as the bottom simulating reflector or BSR on seismic section in the presence of gas-hydrates. Through analysis and scrutinizing of multi-channel seismic (MCS) data, we have detected the BSRs in the Krishna-Godavari (KG), Mahanadi and Andaman regions respectively. Gas-hydrates in these regions have later been recovered by drilling and coring under the Expedition-01 of Indian National Gas-Hydrates Program. This has motivated our efforts to develop methods for the delineation, characterization and assessment of gas-hydrates. By computing seismic attributes like reflection strength, blanking, attenuation and instantaneous frequency, we have demonstrated that these attributes can be used for qualifying and characterizing a gas-hydrate reservoir. We have developed several approaches based on seismic travel time tomography, full-waveform inversion, amplitude versus offset modelling, impedance inversion, each coupled with rock-physics modeling, and applied them to seismic data for delineation and quantitative assessment of gas-hydrates in KG, Andaman and Mahanadi basins. We have also acquired high resolution MCS and wide-angle ocean bottom seismic (OBS) data by specially designing an experiment using the state-of-the-art acquisition system in unexplored areas, and delineated new prospective zones of gas-hydrates in the Mahanadi and KG offshore. Recent success in test production of methane gas from gas-hydrates through carbon dioxide replacement method in the permafrost of Alaska (USA) and by depressurization method in the Nankai Trough off Japan has increased tremendous interests in the national gas hydrates programs of India and many other countries like South Korea, China, Taiwan, New Zealand, Australia, Canada, Germany etc. It is expected that the gas-hydrates will be produced commercially by 2020.


2
 

Deep crustal Shear Zones in the Eastern Ghats Mobile Belt, India: Gondwana correlations

T.R.K.Chetty

CSIR-National Geophysical Research Institute, Hyderabad, 500 007, India
E.mail: trkchetty@gmail.com


ABSTRACT
Shear zones are significant in understanding the physicochemical processes, such as mineralization, magmatism, metamorphism, and deformational patterns and bear remarkable influence on many aspects of earth system science. We present here the structural framework of the Eastern Ghats Mobile Belt (EGMB) that constitutes a net work of deep crustal shear zones. It was possible to identify and recognize these shear zones by involving different spatial data sets, field observations along regional traverses and detailed structural analysis in selected critical areas and outcrop mapping and in conjunction with the available published geological maps. We review and present here field description, distribution, geometry and the kinematics of different shear zones of the EGMB and emphasize their significance in terms of tectonic models and Gondwana correlations.
The shear zones at the cratonic margins such as the Sileru shear zone, Koraput - Rairakhol shear zone and the Northern boundary shear zone represent a long and continuous suture zone extending for over a few hundreds of kilometers and upto lithospheric depths. All the shear zones witnessed multiple events of magmatism, metamorphism and deformation. The stretching lineations show different orientations in different segments and divide the EGMB into several distinct structural domains. All the shear zones are found to be transpressive in character and subjected to repeated reactivation in space and time. Oblique collision and long lived transpressional tectonic regime during Gondwana amalgamation seem to be responsible for the present structural architecture of the EGMB.
The shear zones are the controlling factors for any mineralization, igneous activity, migmatization and retrogression and that they represent ‘key laboratories’ for understanding the geological processes and ultimately the earth’s history. There is a strong need for detailed field based studies involving modern mapping techniques with current tectonic perspectives before we attempt any advanced laboratory based measurements for useful and meaningful interpretations.


3
 

An overview of Coastal Ecosystem Structure, Dynamics and Management - Need for a Holistic Approach
B.S.R. Murthy1 and P.R. Reddy2
1Deputy Director General (Ret), GSI; H.No: 2-2-18/18/4/19, Bagh Amberpet, Hyderabad-500 013
2Scientist ‘G’ (Ret), National Geophysical Research Institute (NGRI), Hyderabad-500007
Email: murthybsr123@gmail.com, parvatarreddy@gmail.com

Abstract
Coastal zones throughout the world have historically been among the most heavily exploited areas because of their rich resources. In coastal countries today an estimated half of the total populations live in coastal zones, and migration from inland areas to the coast is increasing. Not surprisingly, there is also a sharp conflict between the need for immediate consumption or use of coastal resources and the need to ensure the long-term supply of those resources. In many countries this conflict has already reached a critical stage, with large parts of the coastal zone polluted from local or upland sources, fisheries severely degraded or destroyed, wetlands drained, coral reefs dynamited and beaches long since ruined for human enjoyment. If the coastal zones are to be restored, appropriate and effective action is urgently needed. To answer this need, a management system has to be designed: Holistic or Integrated Coastal Zone Management (ICZM) and for this purpose it is essential to first understand the structure and dynamics of coastal ecosystem. We believe that this exposition, even though of basic academic interest, would provide needed introduction to the subject and enable the young researches (interested in carrying out scientific studies and environmental up-gradation activities that basically help the society) in better moulding of their research programmes.


4
A Study on the Possible Oil Spill & Gas Leakage Vulnerable Zones of Gujarat State Using GIS Tools
Ananya Das1 and T. Harinarayana2
1 Centre for research and Development Consultancy (CRDC), CEPT University, Ahmedabad, Gujarat
2 Gujarat Energy Research and Management Institute, Gandhinagar, Gujarat
E mail: ananya_22242@yahoo.com, harinarayana@germi.res.in

ABSTRACT
There are many instances of oil spills and gas leakages in India due to accidents within the industry and also during transmission through pipelines. The spills or leakages are likely to occur near the improper joints. Apart from this, there are a number of other reasons. This study is aimed to analyze all the aspects related to possible oil spills and gas leakages with special reference to Gujarat state. The database considered in this study includes communication network (roads /rail), rivers, elevation, pipeline networks, fault zone, earthquake zone, meteorological data etc. In order to analyse these databases, the well known geographical information system software (GIS) has been used and the possible hazardous locations and the vulnerable zones have been identified by considering the datasets with logical queries. The end maps and results provided from the present study are useful to the industry in order to take precautionary steps and remedial measures that are required to tackle the oil spill and gas leakages in an efficient way.

5
Efficacy of electrode arrays in resistivity prospecting using physical modelling
P. Padmavathi Devi1*, P. Rajendra Prasad2, R. Rajesh3, G. Padalu3 and V.S. Sarma3
1*Senior Research Fellow, Department of Geophysics, Andhra University, Visakhapatnam-3.
2Sir Aurthor Cotton Geo Spatial Chair, Department of Geophysics, Andhra University, Visakhapatnam-3.
3 CSIR - National Geophysical Research Institute, Hyderabad-500 007.
Corresponding author: *padmavathidv399@gmail.com

ABSTRACT
Physical Model experimentation using resistivity profiling over metallic sheet-like target in different orientations has been carried out with different electrode configurations viz., Two-electrode, Three-electrode, Wenner and Dipole-Dipole with an objective to find out the relative merits and demerits of the arrays and to study the efficacy of one electrode configuration over the other. We have carried out experimentation in two ways viz., (i) the target depth (d) is fixed at a particular level and profiles are run with different arrays as mentioned above by changing the array spacings (L) for that particular depth. For this, the conducting target is submerged in the host medium water, in vertical position (q=90°) contained in the model tank and resistivity response characteristics are recorded for all arrays and their spacings in a systematic and sequential way and (ii) the same target is kept in different orientation i.e., in horizontal direction (q=0°) and its depths (d) are changed for a particular array spacing (L) of the array so that an in-depth understanding of the theme can be had i.e., variation of the anomaly with depth, with orientation, with array spacing and with type of the array .
An overall study on efficacy of the electrode arrays over both the targets indicated that the profiles are broadened over horizontal conducting sheet compared to those over a vertical sheet. The reason is that, the area of exposure to the measuring system is very large in comparison with the exposed area of vertical sheet.
Over the vertical conducting sheet, the Wenner apparent resistivity profiles show a W-shaped pattern whereas the profiles show a low only over the horizontal sheet. The other result that emerged out of the comparison of the different electrode arrays is that the two-electrode array gives the simplest and largest anomalies with the small electrode spacings for conducting metallic target. This array gives the best response with regard to amplitude and shape of anomaly. But placing the infinity electrodes puts a practical problem. Finally, Dipole -Dipole array is the next alternative as its response is symmetrical over a vertical sheet, better in shape and amplitude. But the Dipole-Dipole array demands large transmitting source power.


6
New Palaeomagnetic evidences about Deccan Trap Volcanic activity from the magmatic bodies of Kachchh Basin, Northwest India
*Mamilla Venkateshwarlu1, Bindhyachal Pandey2, G. Papanna1, Deo Brat Pathak2, Jai Krishna2
1 CSIR-National Geophysical Research Institute, Uppal Road, Hyderabad -500 007, India
2 Department of Geology, Banaras Hindu University, Varanasi – 221005, India
*Corresponding author: mamila_v@rediffmail.com

ABSTRACT
New Palaeomagnetism results have been obtained from twelve dyke samples that are intruded into the litho units exposed in three different localities, namely, Jumara (Mainland), Kaladongar (Patcham Island) and Kantkote (Wagad, outside the Mainland) in the Kachchh Basin of Gujarat, North West India. The study shows that the dykes from two of the three localities have normal directions while the third has a reverse direction (similar to the Deccan Volcanic Province directions). The combined Virtual Geomagnetic Pole (VGP) provides 34.8 °N and 83.8 °W (dp/dm = 5.12/8.13). This pole is similar to that of the Deccan Super Pole (36.9 °N; 78.7 °W). The findings suggest that wide spread distribution of magmatic activity in the Kachchh basin is coeval with the Deccan lava eruption.


7
Influence of Interplanetary magnetic field on Equatorial Electrojet-Observations from South India
*N. Phani Chandrasekhar1 and S.Thinesh Kumar2
1Magnetic Observatory, CSIR- National Geophysical Research Institute, Hyderabad-500 007
2Indian School of Mines, Dhanbad -826 004
*Corresponding author: phaninelapatla@gmail.com

ABSTRACT
The occurrence of equatorial Counter electrojet (CEJ) and Prompt penetration effects are studied at a newly established equatorial remote station, Vencode (VEN), Kanyakumari Dt, at the southern tip of India. The three month’s dataset (Nov, Dec-2010 and Jan-2011) of VEN along with permanent Hyderabad (HYB) Magnetic Observatory are used in the present study to assess the relationship between the CEJ and prompt penetration events with interplanetary parameters (IPP): Electric field (Ey) / southward component of magnetic field (Bz) and modeled penetration fields. The influence of short-term (~30-60 minutes) and long-term (~02-04 hours) fluctuations of the equatorial ionosphere on the horizontal (H) component of earth’s magnetic field at VEN are explained in terms of change in orientation of IPP. We found a strong correlation between the CEJ events with Bz orientation (north-south-north). Moderate correlation is found between the high frequency components of the derived Equatorial electric field (EEF) with Real time prompt penetration electric field model (PPEFM). The day-to-day variability in Equatorial electrojet (EEJ) strength associated with CEJ events highlight the role of equatorial ionosphere in the present study. Our results from VEN confirm the positive relation of about 70% between CEJ events with Bz polarity.


8
Fractal dimensional analysis of Cyclonic disturbances over the North Indian Ocean
R. Uma1 and R. Samuel Selvaraj2
1Department of Physics, D.G.Vaishnav College, Chennai
2Department of Physics, Presidency College, Chennai
E-mail:umajeel@gmail.com

ABSTRACT
In this paper, we use fractal dimensional analysis to investigate the number of cyclonic disturbance that includes depressions, cyclonic storms and severe cyclonic storms over the North Indian Ocean (comprising Bay of Bengal and Arabian Sea) using the Hurst exponent. We use the rescaled range (R/S) analysis to estimate the Hurst exponent for a period of 104 years (1901-2004) of cyclone data. The value of the Hurst exponent is corroborated by computing the correlogram of the concerned time series. The results are validated by Detrended Fluctuation Analysis (DFA). The distinct value of the Hurst exponent shows the persistence nature of the cyclonic disturbances over the North Indian Ocean.


9
South Indian Convergence Zone Model: A new approach to seasonal forecasting of summer monsoon rainfall in India Part V: Relative roles of major oscillations in Pacific and Indian Oceans in inter-annual variability of Indian summer monsoon rainfall
Onkari Prasad1 and O.P. Singh2
143, Ritu Apartments, A-4 Paschim Vihar, New Delhi-110 063
2India Meteorological Department, Lodi Road, New Delhi-110003
Email: prasadonkari123@yahoo.in; s ingh.op@imd.gov.in

ABSTRACT
El Nino Southern Oscillation (ENSO), which affects the weather over the globe, is considered as one of the major factors in the inter-annual variability of Indian Summer Monsoon (ISM) Rainfall (ISMR). Studies on ISM by the authors have identified an important role of the annual oscillation of the equatorial troughs in Indian Ocean (IO), as monitored in satellite observed cloud data, in inter-annual variability of ISMR. Quantification of the activity of equatorial troughs in Indian ocean during the period January-May in relation to rainfall over India during June-September, i.e., ISMR, and development of a Long Range Forecast (LRF) model, referred to as South Indian Convergence Zone (SICZ) model, have been discussed in Part I of the paper. Verification of real time LRF for the past 22 years (1990-2011) for India as a whole, i.e., ISMR, as well as in meteorological sub-divisions of India ( numbering 36 ), as discussed in Pt II and Pt III of the paper respectively, have shown that SICZ model has produced reasonably good forecasts of summer monsoon rainfall for more than 2 decades now. In this part of the paper we have examined the relative roles of major oscillations in Pacific and Indian Oceans in inter-annual variability of ISMR. It has been shown that SST anomalies in Nino 3.4 region ( 5°S- 5°N, 120°W -170° W ) could provide good LRF of ISMR during ‘normal’ monsoon years. However, all extreme seasons (‘excess’ / ’drought’ ) could not be foreshadowed. On the other hand, SICZ model, has been able to foreshadow not only ‘normal’ monsoons but the extreme seasons also during the past 22 years. This has indicated a dominant role of Indian Ocean in the development of ISM and its inter-annual variability. The relative roles of Pacific and Indian Oceans in the inter-annual variability of ISMR are discussed in this part of the paper.


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