With the rapid growth in population and economic development, emissions of greenhouse gases (GHGs) from the Indian subcontinent have sharply increased during recent decades. However, evaluation of ...regional fluxes of GHGs and characterization of their spatial and temporal variations by atmospheric inversions remain uncertain due to a sparse regional atmospheric observation network. As a result of an Indo-French collaboration, three new atmospheric stations were established in India at Hanle (HLE), Pondicherry (PON) and Port Blair (PBL), with the objective of monitoring the atmospheric concentrations of GHGs and other trace gases. Here we present the results of the measurements of CO2, CH4, N2O, SF6, CO, and H2 from regular flask sampling at these three stations over the period 2007-2011. For each species, annual means, seasonal cycles and gradients between stations were calculated and related to variations in natural GHG fluxes, anthropogenic emissions, and monsoon circulations. Covariances between species at the synoptic scale were analyzed to investigate the likely source(s) of emissions. The flask measurements of various trace gases at the three stations have the potential to constrain the inversions of fluxes over southern and northeastern India. However, this network of ground stations needs further extension to other parts of India to better constrain the GHG budgets at regional and continental scales.
We use broad-band teleseismic data recorded at eight sites along a north—south profile from Karimganj (24.84°N, 92.34°E), south of the eastern Shillong Plateau, to Bomdilla (27.27°N, 92.41°E) in the ...eastern Lesser Himalaya, to determine the seismic characteristics of the crust in northeastern India. We also analyse data from the Chinese Digital Seismic Network station at Lhasa and INDEPTHII stations located on the southern Tibetan Plateau north of our profile, to extend the seismic images of the crust further northwards. Although the northeastern Indian stations and the Tibetan the well-recognized uniformity of the Himalaya along strike make this comparison of the two profiles meaningful. Receiver functions calculated from these data show that the crust is thinnest (∼35–38 km) beneath the Shillong Plateau. Receiver functions at Cherrapunji, on the southern edge of the Shillong Plateau, have a strong azimuthal dependence. Those from northern backazimuth events show that the Moho beneath the southernmost Shillong Plateau is at a depth of ∼38 km while receiver functions from southern backazimuth events indicate that the Moho beneath the northernmost Bengal Basin is at a depth of ∼44 km. Receiver functions from sites on the Brahmaputra Valley demonstrate that the Moho is deeper by ∼5–7 km than below the Shillong Plateau, a result which agrees with the hypothesis that the Shillong Plateau is supported by shearing stress on two steep faults that cut through the crust. Further north of the eastern Himalayan foredeep, the Moho dips gently northwards, reaching a depth of ∼48 km beneath Bomdilla in the Lesser Himalaya, and 88 km below Lhasa in Tibet. Using the crustal velocity models obtained from receiver function inversions, we redetermined focal depths of well-recorded earthquakes across this part of the Indo-Tibetan collision zone and find all of these to occur within the crust. Hence we find no evidence for bimodal depth distribution of earthquakes beneath this region of northeastern India.
Full text
Available for:
BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
Earthquakes. Himalayan seismic hazard Bilham, R; Gaur, V K; Molnar, P
Science (American Association for the Advancement of Science),
2001-Aug-24, 20010824, Volume:
293, Issue:
5534
Journal Article
Peer reviewed
Full text
Available for:
BFBNIB, NMLJ, NUK, PNG, SAZU, UL, UM, UPUK
GPS data reveal that the Brahmaputra Valley has broken from the Indian Plate and rotates clockwise relative to India about a point a few hundred kilometers west of the Shillong Plateau. The GPS ...velocity vectors define two distinct blocks separated by the Kopili fault upon which 2–3 mm/yr of dextral slip is observed: the Shillong block between longitudes 89 and 93°E rotating clockwise at 1.15°/Myr and the Assam block from 93.5°E to 97°E rotating at ≈1.13°/Myr. These two blocks are more than 120 km wide in a north‐south sense, but they extend locally a similar distance beneath the Himalaya and Tibet. A result of these rotations is that convergence across the Himalaya east of Sikkim decreases in velocity eastward from 18 to ≈12 mm/yr and convergence between the Shillong Plateau and Bangladesh across the Dauki fault increases from 3 mm/yr in the west to >8 mm/yr in the east. This fast convergence rate is inconsistent with inferred geological uplift rates on the plateau (if a 45°N dip is assumed for the Dauki fault) unless clockwise rotation of the Shillong block has increased substantially in the past 4–8 Myr. Such acceleration is consistent with the reported recent slowing in the convergence rate across the Bhutan Himalaya. The current slip potential near Bhutan, based on present‐day convergence rates and assuming no great earthquake since 1713 A.D., is now ~5.4 m, similar to the slip reported from alluvial terraces that offsets across the Main Himalayan Thrust and sufficient to sustain a Mw ≥ 8.0 earthquake in this area.
Key Points
New GPS velocity field in eastern HimalayaShillong Plateau is independent from IndiaStrain accumulated since the last earthquake is sufficient for a M > 8 earthquake
Full text
Available for:
BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
In this article, biocomposites derived from a starch-glycerol biodegradable matrix reinforced with jute fibers were fabricated using the wet hand lay-up and compression moulding techniques. Samples ...having different weight percentages of jute fiber in the starch matrix were analyzed. The fiber’s surface was chemically treated by alkaline sodium hydroxide to improve the interphase bonding between the fiber and the matrix. Tensile tests for the composites were done and the sample with highest tensile strength was selected for further tests that included water absorption (WA), scanning electron microscopy (SEM) and thermal analysis (TA). It has been concluded that the ultimate tensile strength was found to be maximum for the composition of 15% fiber by weight composite as 7.547 MPa without epoxy coating and 10.43 MPa with epoxy coating. The major disadvantage of the biocomposite is its high WA property, which in this study was inhibited by the epoxy resin layer. Herein, the results of various tests done disclose a noteworthy improvement in the overall properties of bio-composite, in comparison to the neat biodegradable starch matrix.
We present results of a Rayleigh and Love wave group velocity dispersion study of the Indo‐Eurasian collision zone. Group velocity dispersion curves are measured and combined to produce dispersion ...maps for 10–70 s period Rayleigh waves from 4054 paths and for 15–70 s Love waves from 1946 paths. Group velocity maps benefit from the inclusion of data recorded at a large number of stations within India, an advantage over previous global studies. This has the largest impact at short periods as a result of the improved path length distribution. Synthetic tests are used to estimate resolution, which ranges from 3° to 5° on the continents for Rayleigh wave maps and from 5° to 7.5° for Love wave maps. Group velocities correspond well with known geological and tectonic features and show good correlation with sediment thickness at short periods. The cratons of the Indian Shield can be distinguished in the short‐period and midperiod group velocities. Group velocities are slow across Tibet until 70 s whereas the cratonic cores of the Indian Shield appear as a high velocity anomaly at 70 s. Dispersion curves extracted from the Rayleigh wave group velocity maps are inverted for shear wave velocity as a function of depth for profiles across India and Tibet. The relationship between shear velocity contours and the Moho indicated by receiver function studies has been used to obtain a first‐order estimate of crustal thickness across the collision zone. Results suggest a slow Tibetan midcrust and low sub‐Moho velocities beneath the central and northeastern Tibetan Plateau.
We present an improved 3-D shear wave velocity image of the uppermost mantle beneath the Bay of Bengal (BoB), the Bengal basin and the adjoining Indian shield to their west. Shear wave velocities ...were inverted from fundamental mode Rayleigh wave group velocities calculated along 21,600 crisscrossing paths from cross correlation of ambient noise as well earthquake seismograms. This study shows the hitherto unsuspected existence of distinct lithospheres in the eastern and western Bay of Bengal, on either side of 86° E longitude, but understandable in terms of their different origins and ages. The western Bay of Bengal, with greater than 120 km thick layered lithosphere has a shear wave velocity of 4.7 km/s beyond the depth of 90 km. This velocity structure is in lateral continuation with the high velocity in the adjacent cratonic India. The lithosphere thickening can be explained to be the result of conductive cooling of an oceanic plate with a temperature of 1300 ± 50 °C at its base. The remarkable similarity between the velocity structure of the western BoB and the adjoining Indian craton, which could be fortuitous, however, suggests the untested possibility that the fracture plane mediating the initial break-up of India from Antarctica might have been inclined towards the former creating asymmetrically spreading oceanic crust over a cratonic upper mantle. The eastern Bay of Bengal (BoB), in contrast, has thinner lithosphere (60–75 km) with minimum velocity of ~4.2 km/s which is anomalously low for an old ocean. This significant thinning could have been caused by a number of factors such as reheating of the original lithosphere arising from a thermal boundary layer instability or westward flow of mantle due to slab rollback of subducting Indian lithosphere in the Andaman arc.
•Improved 3-D shear wave velocity image of the Bay of Bengal and Bengal basin lithosphere.•Identification of distinct lithospheres in the eastern and western Bay of Bengal, on either side of 86° E longitude.•Continuity of the Indian craton upper mantle structure beneath the western Bay of Bengal.•86° E as a lithospheric scale boundary such as Fracture Zone with large age contrast or continent-ocean boundary.•Eastern Bay of Bengal with thinned lithosphere (60–75 km) suggest its recent reheating.
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
► The post treatment systems of UASB effluent treatment treating sewage are discussed. ► The NBMS based treatment concept was suggested for the treatment of the sewage. ► High rate micro-aerobic ...methods were suggested for the up gradation of UASB based existing sewage treatment plants (STPs) to achieve desired effluent quality for disposal or for reuse. ► An economic evaluation of some of the emerging options was described. ► This paper definitely helps the decision or policy makers, engineers and researchers/scientists working in PuSAN sector.
The upflow anaerobic sludge blanket (UASB) process is reported to be a sustainable technology for domestic wastewaters treatment in developing countries and for small communities. However, the inability of UASB process to meet the desired disposal standards has given enough impetus for subsequent post treatment. In order to upgrade the UASB based sewage treatment plants (STPs) to achieve desired effluent quality for disposal or for reuse, various technological options are available and broadly differentiated as primary post-treatment for the removal of organic and inorganic compounds and suspended matter; secondary post-treatment for the removal of hardly degradable soluble matter, colloidal and nutrients; and polishing systems for removals of pathogens. Hence, this paper discusses the different systems for the treatment of UASB reactor effluent treating sewage. Additionally, a comparative review, an economic evaluation of some of the emerging options was conducted and based on the extensive review of different integrated combination, i.e. UASB-different aerobic systems, a treatment concept based on natural biological mineralization route recognized as an advanced technology to meet all practical aspects to make it a sustainable for environmental protection, resource preservation and recovering maximum resources.
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
ABSTRACT
1ES 1959+650, a high-energy peaked BL Lac object (HBL) with redshift z = 0.047, is known to exhibit flux and spectral variability in different energy bands. In this work, we primarily ...considered the simultaneous Fermi-LAT and Swift-XRT data of 1ES 1959+650 to study the flux and spectral variability in the energy ranges (0.1–300 GeV) and (0.6–10 keV), respectively. Using the Fermi-LAT light curve, a stretch of quiescent state and three high flux states of the source were identified. The flux and the spectral variability were studied using flare profiles and flux-index loops. In the γ-ray energies, 1ES 1959+650 clearly showed the evolution ‘softer-when-brighter’ whereas in the X-rays it showed the trend ‘harder-when-brighter’. 1ES 1959+650 also showed quick changes in spectral shape in the γ-ray band when the γ-ray flux was changing during the flares. The spectral energy distributions (SEDs) of the source were constructed using simultaneous data from Fermi-LAT, Swift-XRT, Swift-UVOT during its evolution. The TeV data from TACTIC imaging telescope were also used to construct the SED in the quiescent state. The spectral modelling of the SEDs revealed that due to the spectral variability of 1ES 1959+650, the standard leptonic one zone model cannot be used to explain the emission from this source. Instead a two zone leptonic model is needed to explain the observed SEDs from this blazar.
Abstract
We present GPS velocities in Kashmir valley and adjoining regions from continuous Global Positioning System (cGPS) network during 2008 to 2019. Results indicate total arc normal shortening ...rates of ~ 14 mm/year across this transect of Himalaya that is comparable to the rates of ~ 10 to 20 mm/year reported else-where in the 2500 km Himalaya Arc. For the first time in Himalayas, arc-parallel extension rate of ~ 7 mm/year was recorded in the Kashmir valley, pointing to oblique deformation. Inverse modeling of the contemporary deformation rates in Kashmir valley indicate oblique slip of ~ 16 mm/year along the decollement with locking depth of ~ 15 km and width of ~ 145 km. This result is consistent with the recorded micro-seismicity and low velocity layer at a depth of 12 to 16 km beneath the Kashmir valley obtained from collocated broadband seismic network. Geodetic strain rates are consistent with the dislocation model and micro-seismic activity, with high strain accumulation (~ 7e−08 maximum compression) to the north of Kashmir valley and south of Zanskar ranges. Assuming the stored energy was fully released during 1555 earthquake, high geodetic strain rate since then and observed micro-seismicity point to probable future large earthquakes of Mw ~ 7.7 in Kashmir seismic gap.
Full text
Available for:
IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
PDF
