Regional tectonic trends on the inner continental shelf off Konkan and Central West Coast of India

Satellite imagery and offshore magnetic data were analysed to correlate regional tectonic elements on the inner continental shelf off Konkan and the adjacent Deccan plateau. Three statistically important lineament trends—N-S, WNW-ESE and ENE-WSW—that prevail on land are correlatable well with the offshore trends. This positive correlation suggests simultaneous deformation. The major magnetic lineament observed off Jaigad Bay, west coast of India, may be the extension of onshore lineaments. The correlation of both the offshore and onshore trends indicates that the fracture pattern of the crystalline basement has also controlled the offshore structural pattern.     

Analysis of the Tsunami of December 26, 2004, on the Kerala Coast of India—Part I: Amplitudes

The Indian Ocean tsunami of December 26, 2004, not only affected the Bay of Bengal coast of India but also part of the Arabian Sea coast of India. In particular, the tsunami caused loss of life and heavy damage on some parts of the Kerala coast in southwest India. The tsunami traveled west, south of Sri Lanka, and some of the tsunami energy was diffracted around Sri Lanka and the southern tip of India and moved northward into the Arabian Sea. However, tsunami, being a long gravity wave with a wave length of a few hundred kilometers, has to take a wide turn. In that process, it missed the very southern part of the Kerala coast and did not achieve large amplitudes there. However, further north, the tsunami achieved amplitudes of upto 5 m and caused loss of life and significant damage. Here we identify the physical oceanographic processes that were responsible for selective amplification of the tsunami in certain locations.     

Sound velocity,density, and related properties along a transect across the Bay of Bengal

Physical properties, sound velocity and density of 95 core samples from ten locations along a transect (parallel to 15°N latitude) across the Bay of Bengal were measured. Results indicate that sound velocities range from 1,482 to 1,679 m/s (av: 1,583 m/s) and densities from 1,338 to 1,757 kg/m³ (av: 1,527 kg/m³). It has been observed that dark colored clays and sandy clays show higher values of sound velocity and density than the average values. A comparative study of the same with that of the sediment cores collected from the Norwegian basin, Mediterranean Sea, and Hatteras, Nares Abyssal plains, western North Atlantic Ocean was done.     

Solar and galactic cosmic‐ray records of the Fermo (H) chondrite regolith breccia

Abstract— ‐We demonstrate the presence of solar flare as well as neutron capture effects in the isotopic composition of rare gases in the Fermo regolith breccia acquired on its parent body based on the measurements of tracks, rare gases and radionuclides. The track density along a 3.2 cm long core decreases by a factor of about 6 and by more than a factor of 13 within the meteorite, indicating small (2–9 cm) and asymmetrical ablation. Rare gases show a large trapped component; the isotopic ratios, particularly ²⁰Ne/²²Ne ? 11 and ²⁰Ne/³⁶Ar = 10 are indicative of a solar component. The galactic cosmic‐ray exposure age is determined to be 8.8 Ma. Activities of a dozen radionuclides ranging in half‐life from 16 day ⁴⁸V to 0.73 Ma ²⁶Al are consistent with their expected production rates. Track, rare gas and radionuclide data show that the meteoroid was a small body (≤ 120 kg) and had a simple, one‐stage exposure history to cosmic rays in the interplanetary space. However, ⁸²Kr and ¹²⁸Xe show an excess due to neutron irradiation on the parent body of the meteorite. The presence of solar gases and the neutron capture effects indicate several stages of irradiation on the parent asteroid. The chemical composition of Fermo confirms that it belongs to the H group of ordinary chondrites with lithic clasts having varying compositions. δ¹⁵N is found to be 8.3 ± 1.2%0, close to the typical values observed in H chondrites.     

On the possible origin of troilite‐metal nodules in the Katol chondrite (L6‐7)

Microtextural study of a single troilite‐metal nodule (TMN) from the Katol L6‐7 chondrite, a recent fall (May, 2012) in India suggests that the TMN is primarily an aggregate of submicron‐scale intergrowth of troilite and kamacite (mean Ni: 6.18 wt%) juxtaposed with intensely fractured silicates, mainly olivine (Fa: 25 mole%), low‐Ca pyroxene (Fs: 21.2 mole%), and a large volume of maskelynite. Evidence of shock textures in the TMN indicates a high degree of shock metamorphism that involves plagioclase‐maskelynite and olivine‐wadsleyite/ringwoodite transformations and formation of quenched metal‐sulfide melt textures due to localized shear‐induced frictional melting. It is inferred that the TMN formation is an independent, localized event by a high energy impact and its subsequent incorporation in the ejected chondritic fragment of the parent body. Katol chondrite has been calibrated with a peak shock pressure of S5 (~45 GPa) after Stöffler et al. (1991), whereas peak shock pressure within the TMN exceeds the shock facies S6 (>45 GPa) following Bennett and McSween (1996) and Stöffler et al. (1991). Overall, the shock‐thermal history of the Katol TMN is dissimilar as compared to the host chondrite.     

Magnetic studies over the northern extension of the Prathap Ridge complex,eastern Arabian Sea

The northern parts of the Prathap and Laccadive Ridge system, eastern Arabian Sea, consist of three parallel basement ridge peaks at varied depths. The topographic highs are associated with either well-developed or subdued magnetic signatures. Model studies, constrained by seismic results, determine the varied nature and depth to the top of the causative basement bodies. Similarities of the geophysical signatures of the ridges and their structural resemblance perhaps point to their common origin. Hence we propose that the Prathap Ridge complex may be a part of the Chagos-Laccadive Ridge system and formed because of the Reunion hotspot activity.     

Relationship in metastasis of coal fire and land use/cover using thermal imagery and support vector machine classifier

The objective of the present study was to delineate temporal and spatial changes in the coal fire and land use/cover within Bastacolla area of Jharia coal field. Studying this variation helped to decipher interconnection among the dynamics of the coal fire and concomitant changes in land use/cover. The detection of coal fires during a span of 14 years along with transitioning land use/cover was cost-effective and enabled planning for management of coal resources and environment. Landsat series of satellite data of 2002, 2009, 2013, and 2016 were processed for generating land surface temperature profiles vis-a-vis classified land use/cover of the study area. A single cut-off temperature was derived for mapping of coal fires using land surface temperature profile from 2002 to 2016. The satellite images were classified using support vector machines, and for depicting land use/cover change, post-classification change detection was done. Classification accuracy obtained was excellent with kappa coefficient ranging from 0.897 for classified image of 2002 to 0.799 for classified image of 2016. Results revealed that coal fires had shifted to the central west part of the area. Furthermore, pockets of coal fire from northern and eastern part of the study area have diminished. OB dumps and coal quarry/coal dump may be attributed towards the spatial change in coal fire while; OB dumps showed connotation with the highest temperature zones. Ground verifications for temperature profiles and coal fires were carried out using thermal camera which enunciated good agreement with results.