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Jogi P.,Osmania University | Mounika K.,Osmania University | Padmaja M.,Osmania University | Lakshmi M.,National Geophysical Research Institute NGRI | Gyanakumari C.,Osmania University
E-Journal of Chemistry | Year: 2011

Complexes of Cu(II), VO(IV), Mn(II), Co(II), Ni(II) and Zn(II) with a Schiff base derived from 2-(aminomethyl)benzimidazole and thiophene-2- carbaxaldehyde (1-(1H-benzimidazol-2-yl)-N-[(E) thiophenylmethylidene] methanamine-BNTM) were successfully synthesized. The complexes have been characterized using chemical analysis, spectroscopic methods (IR, UV-Visible, 1 H- NMR, 13C-NMR and ESR), Thermal studies, conductometric and magnetic data. According to these data, we proposed an octahedral geometry to all the metal complexes. Antibacterial activity of the ligand and its metal complexes were studied against two gram-negative bacteria; Escherichia coli, Pseudomonas aeruginosa and two gram-positive bacteria; Bacillus subtilis, Staphylococcus aureus. It has been found that all the complexes are antimicrobially active and show higher activity than ligand. © Copyright E-Journal of Chemistry 2004-2011. Source

Naganjaneyulu K.,National Geophysical Research Institute NGRI | Santosh M.,Kochi University
Journal of Asian Earth Sciences | Year: 2011

The Madurai Block in southern India is considered to represent the eroded roots of an arc-accretionary complex that developed during the subduction-collision tectonics associated with the closure of the Mozambique Ocean and final suturing of the crustal fragments within the Gondwana supercontinent in the Late Neoproterozoic-Cambrian. Here we present a magnetotelluric (MT) model covering the main collisional suture (Palghat-Cauvery Suture Zone) in the north into the central part of the Madurai Block in the south comprising data from 11 stations. Together with a synthesis of the available seismic reflection data along a N-S transect further south within the Madurai Block, we evaluate the crustal architecture and its implications on the tectonic development of this region. According to our model, the predominantly south dipping seismic reflectors beneath the Madurai Block define a prominent south-dipping lithological layering with northward vergence resembling a thrust sequence. We interpret these stacked layers as imbricate structures or mega duplexes developed during subduction-accretion tectonics. The layered nature and stacking of contrasting velocity domains as imaged from the seismic profile, and the presence of thick (>20. km) low resistivity layers 'floating' within high resistivity domains as seen from MT model, suggest the subduction of a moderately thick oceanic crust. We identify several low resistivity domains beneath the Madurai Block from the MT model which probably represent eclogitised remnants of oceanic lithosphere. Their metamorphosed and exhumed equivalents in association with ultrahigh-temperature metamorphic orogens have been identified from surface geological studies. Both seismic reflections and MT model confirm a southward subduction polarity with a progressive accretion history during the northward migration of the trench prior to the final collisional assembly of the crustal blocks along the Palghat-Cauvery Suture Zone, the trace of the Gondwana suture in southern India. © 2010 Elsevier Ltd. Source

Dundar S.,German Research Center for Geosciences | Kind R.,German Research Center for Geosciences | Kind R.,Free University of Berlin | Yuan X.,German Research Center for Geosciences | And 14 more authors.
Geophysical Journal International | Year: 2011

We analyse data from seismic stations surrounding the Alboran Sea between Spain and North Africa to constrain variations of the lithosphere-asthenosphere boundary (LAB) in the region. The technique used is the receiver function technique, which usesS-to-Pconverted teleseismic waves at the LAB below the seismic stations. We confirm previous data suggesting a shallow (60-90km) LAB beneath the Iberian Peninsula and we observe a similarly shallow LAB beneath the Alboran Sea where the lithosphere becomes progressively thinner towards the east. A deeper LAB (90-100km) is observed beneath the Betics, the south of Portugal and Morocco. The structure of the LAB in the entire region does not seem to show any indication of subduction related features. We also observe goodPreceiver function signals from the seismic discontinuities at 410 and 660km depth which do not indicate any upper-mantle anomaly beneath the entire region. This is in agreement with the sparse seismic activity in the mantle transition zone suggesting the presence of only weak and regionally confined anomalies. © 2011 The Authors Geophysical Journal International © 2011 RAS. Source

Naganjaneyulu K.,National Geophysical Research Institute NGRI | Santosh M.,Kochi University
Journal of Geodynamics | Year: 2010

The southern Indian crustal fragment occupied a central position within the Late-Neoproterozoic-Cambrian Gondwana supercontinent assembly. Here we synthesize the available geophysical data that includes gravity, seismic tomography, deep seismic sounding (DSS) and magnetotellurics (MT) from the Palghat-Cauvery Suture Zone (PCSZ), which is considered as a trace of the Gondwana-forming suture in southern India, as well as the surrounding regions to delineate the crustal architecture and tectonic history of the region. An increased crustal thickness immediately north of the PCSZ is correlated to crustal thickening associated with the subduction-collision processes during continental amalgamation. A prominent gravity low of about -45m gal beneath Kodaikanal in the central Madurai Block, south of the PCSZ might suggest the deep root of a thick magmatic arc. Deep seismic studies in and around Chennimalai at the central domain of the PCSZ indicate the presence of ca. 10km thick low velocity (6.0km/s) layer at mid-crustal depths. The gravity model indicates a high density (2.80gm/cm3) layer corresponding to these depths. Two-dimensional MT model shows highly resistive (>20,000Ω-m) felsic upper crust down to 15-16km all along the profile. The resistivity of the mid-crust is more than 10,000Ω-m and the resistivity of the lower crustal domains is in the range of 500-3000Ω-m. The MT model and revised gravity model, constrained by MT, show a southward dipping low resistive zone (<100Ω-m) and a high density region at a depth range of 15-45km beneath the Chennimalai dome within the PCSZ. The interpretation of magnetotelluric and revised gravity model confirm the PCSZ to be the trace of a major suture zone, and correlate with a plate tectonic model of subduction-collision-accretion tectonics along this zone related to the final amalgamation of the Gondwana supercontinent. © 2009 Elsevier Ltd. Source

Jaiswal R.K.,National Geophysical Research Institute NGRI | Singh A.P.,Institute of Seismological Research | Rastogi B.K.,Institute of Seismological Research | Murty T.S.,University of Ottawa
Natural Hazards | Year: 2011

We present the seismic energy, strain energy, frequency-magnitude relation (b-value) and decay rate of aftershocks (p-value) for the aftershock sequences of the Andaman-Sumatra earthquakes of December 26, 2004 (Mw 9.3) and March 28, 2005 (Mw 8.7). The energy released in aftershocks of 2004 and 2005 earthquake was 0.135 and 0.365% of the energy of the respective mainshocks, while the strain release in aftershocks was 39 and 71% for the two earthquakes, respectively. The b-value and p-value indicate normal value of about 1. All these parameters are in normal range and indicate normal stress patterns and mechanical properties of the medium. Only the strain release in aftershocks was considerable. The fourth largest earthquake in this region since 2004 occurred in September 2007 off the southern coast of Island of Sumatra, generating a relatively minor tsunami as indicated by sea level gauges. The maximum wave amplitude as registered by the Padang, tide gauge, north of the earthquake epicenter was about 60 cm. TUNAMI-N2 model was used to investigate ability of the model to capture the minor tsunami and its effect on the eastern Indian Coast. A close comparison of the observed and simulated tsunami generation, propagation and wave height at tide gauge locations showed that the model was able to capture the minor tsunami phases. The directivity map shows that the maximum tsunami energy was in the southwest direction from the strike of the fault. Since the path of the tsunami for Indian coastlines is oblique, there were no impacts along the Indian coastlines except near the coast of epicentral region. © 2010 Springer Science+Business Media B.V. Source

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