Council of Scientific and Industrial Research National Geophysical Research Institute

Hyderabad, India

Council of Scientific and Industrial Research National Geophysical Research Institute

Hyderabad, India
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Rekapalli R.,Council of Scientific and Industrial Research National Geophysical Research Institute | Tiwari R.K.,Council of Scientific and Industrial Research National Geophysical Research Institute | Sen M.K.,University of Texas at Austin | Vedanti N.,Council of Scientific and Industrial Research National Geophysical Research Institute
Journal of Applied Geophysics | Year: 2017

Noises and data gaps complicate the seismic data processing and subsequently cause difficulties in the geological interpretation. We discuss a recent development and application of the Multi-channel Time Slice Singular Spectrum Analysis (MTSSSA) for 3D seismic data de-noising in time domain. In addition, L1 norm based simultaneous data gap filling of 3D seismic data using MTSSSA also discussed. We discriminated the noises from single individual time slices of 3D volumes by analyzing Eigen triplets of the trajectory matrix. We first tested the efficacy of the method on 3D synthetic seismic data contaminated with noise and then applied to the post stack seismic reflection data acquired from the Sleipner CO2 storage site (pre and post CO2 injection) from Norway. Our analysis suggests that the MTSSSA algorithm is efficient to enhance the S/N for better identification of amplitude anomalies along with simultaneous data gap filling. The bright spots identified in the de-noised data indicate upward migration of CO2 towards the top of the Utsira formation. The reflections identified applying MTSSSA to pre and post injection data correlate well with the geology of the Southern Viking Graben (SVG). © 2017 Elsevier B.V.


Siva Kumar N.,King Saud University | Dharmendra V.,Agilent Technologies | Sreenivasulu V.,Jinan University | Asif M.,King Saud University | And 2 more authors.
Metals | Year: 2017

A new method for the separation, pre-concentration and accurate determination of trace amounts of Pb and Cd in water samples using Amberlite XAD-16 resin functionalized with a new chelating ligand, 3-(2-hydroxyphenyl)-1H-1,2,4-triazole-5(4H)-thione (HTT), Amberlite XAD-16-HTT and inductively coupled plasma atomic emission spectrometry (ICP-AES) is reported in the present study. Fourier transform infrared (FTIR) spectroscopy was used to characterize the chelating resin. The effects of analytical parameters such as the pH of the medium, amount of adsorbent, type and volume of eluent, flow rate of the sample solution, volume of the sample solution, and matrix interference on the retention of metal ions were investigated. Also, 1 M HNO3 was used for the elution of the sorbed metals, and ICP-AES was used for the analysis of elutes offline. The results indicate that pH 5 is the optimum pH for the sorption of Pb and Cd ions. The limit of detection was found to be 0.16 and 0.22 µg/L for Pb and Cd, respectively, by applying a pre-concentration factor of 50. The method was validated using the international water reference material (NIST 1643e). The developed enrichment method has a high selectivity, sensitivity, and reproducibility; this method was successfully applied for the determination of Pb and Cd in surface water samples collected in Nellore District, Penner River belt as well as Bay of Bengal, Andhra Pradesh, India. © 2017 by the authors. Licensee MDPI, Basel, Switzerland.


Vijaya Kumar T.,Council of Scientific and Industrial Research National Geophysical Research Institute | Bhaskar Rao Y.J.,Council of Scientific and Industrial Research National Geophysical Research Institute | Plavsa D.,Curtin University Australia | Collins A.S.,University of Adelaide | And 3 more authors.
Bulletin of the Geological Society of America | Year: 2017

The Southern Granulite terrane, southern India, comprises a vast exposure of deep crust and forms a key region in the reconstruction of the Gondwana supercontinent. An E-W-trending crustal-scale shear zone, the Palghat-Cauvery suture zone system, which formed during the late Neoproterozoic-Cambrian (0.75-0.50 Ga), marks a prominent terrane boundary separating terranes with a predominantly late Neoarchean (ca. 2.5 Ga) regional granulite metamorphism to the north from those with an Ediacaran-Cambrian (0.63-0.50 Ga) regional granulite metamorphism to the south. Focusing on the younger granulite metamorphic domains, we present here new zircon U-Pb ages and Hf isotopic compositions for 11 charnockite orthogneisses from the Madurai, Trivandrum, and Nagercoil blocks and contribute to the resolution of the age of their magmatic protoliths. This study shows that the charnockite orthogneisses south of the Palghat-Cauvery suture zone relate to a minimum of four distinct episodes of felsic magmatism centered at: Ca. 2.62-2.46 Ga, ca. 2.05-1.84 Ga, ca. 1.0- 0.9 Ga, and ca. 0.80-0.76 Ga, pertaining to the Siderian, Orosirian, and Tonian Periods. Hafnium isotope analyses of zircon grains from the charnockite gneisses suggest that the protoliths of the ca. 2.05-1.98 Ga gneisses from the Trivandrum and Nagercoil blocks and the ca. 1.0-0.9 Ga gneisses along the southeastern Madurai block involved a significant juvenile magma component, while the protoliths of charnockite gneisses elsewhere in the Madurai block formed mainly through recycling of older crust up to ca. 3.2 Ga. A regional granulite-facies metamorphic imprint during the Ediacaran-Cambrian marked an advanced stage in the amalgamation of the Madurai, Trivandrum, and Nagercoil blocks into the East African orogen and its collision with the Dharwar craton. © 2016 Geological Society of America.


Kumar D.,Council of Scientific and Industrial Research National Geophysical Research Institute | Mondal S.,Council of Scientific and Industrial Research National Geophysical Research Institute | Nandan M.J.,Council of Scientific and Industrial Research National Geophysical Research Institute | Harini P.,Council of Scientific and Industrial Research National Geophysical Research Institute | And 2 more authors.
Arabian Journal of Geosciences | Year: 2016

Groundwater investigation in a crystalline rock is a crucial task. A study was carried out at Choutuppal Telangana, India, under the pivotal research project of societal relevance. High-resolution electrical resistivity tomography (ERT) and time-domain-induced polarization (TDIP) dataset were collected in a granitic terrain to solve the groundwater problem as people are facing acute shortage of drinking water in the study area. The interpreted results derived from two-dimensional (2D) inverted resistivity models revealed substantial resistivity contrast between the weathered and massive granite and delineated three groundwater prospects zones, where the degree of weathering of fractured granite decreases with depth. On the other hand, the induced polarization (IP) results reflect marginal chargeability contrast, which indicates groundwater prospect zone. The basement of the hard rock aquifer system is clearly delineated showing very high resistivity with a range from 5000 to ~4 × 105 Ohm.m, which is confirmed by drilling at two places. Both the wells are drilled during the month of April and June, 2013, which are productive with a yield varying from 82.14 to 105 l/min. This study may help in future planning for groundwater exploration strategy and development for groundwater resources. © 2016, Saudi Society for Geosciences.


Sundararajan N.,Sultan Qaboos University | Seshunarayana T.,Council of Scientific and Industrial Research National Geophysical Research Institute
Arabian Journal of Geosciences | Year: 2013

Shear wave velocity (VS) estimation is of paramount importance in earthquake hazard assessment and other geotechnical/geo engineering studies. In our study, the shear wave velocity was estimated from ground roll using multichannel analysis of surface wave (MASW) technique making use of dispersive characteristics of Rayleigh type surface waves followed by imaging the shallow subsurface basaltic layers in an earthquake-prone region near Jabalpur, India. The reliability of MASW depends on the accurate determination of phase velocities for horizontally traveling fundamental mode Rayleigh waves. Inversion of data from surface waves resulted in a shear wave velocity (VS) in the range of 200-1,200 m/s covering the top soil to weathering and up to bedrock corresponding to a depth of 10-30 m. The P-wave velocity (VP) obtained from refraction seismic studies at these locations found to be comparable with VS at an assumed specific Poisson's ratio. A pair of selected set of VS profiles over basalt which did not result in a hazardous situation in an earthquake of moderate magnitude are presented here as a case study; in other words, the shear wave velocity range of more than 200 m/s indicate that the area is highly unlikely prone to liquefaction during a moderate or strong earthquake. The estimated depth to basalt is found to be 10-12 m in both the cases which is also supported by refraction studies. © 2013 Saudi Society for Geosciences.

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