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91.
The Bhuj region, Kutch, India, is included in the highly seismic zonation map of India. The Kutch is a rift basin and so far has experienced three major earthquakes that are due to reverse fault mechanism, which in turn have been ascribed to compressive stresses. Origin of these stresses is considered to be due to north–south convergence of the Indian Plate with the Tibetan plate, and this has placed the entire Indian Plate under the compressive stress regime. Analysis of the stress pattern in the Bhuj region, therefore, has been carried out by extracting lineaments with the help of remote sensing data for the pre- and post-earthquake periods of 26 January 2001 earthquake. For this purpose, the area has been segmented into four sectors. The lineament frequency and the percent frequency from each sector and also for the whole area have been worked out. Resolution of stress on the principle of triaxial ellipsoid has been worked out for each sector and also for the whole area. There results a temporal change in the stress pattern in each sector and also for the whole area. However, the direction of horizontal maximum compressive stress for the whole area appears to be in N 10°E in the pre-earthquake period that has changed to N 10°W in the post-earthquake period. Thus, temporal change in the horizontal maximum compressive stress direction as N 23°E, inferred by Gowd et al. (J Geophy Res 97:11879–11888, 1992) to N 10°E prior to and N 10°W in the post-earthquake period, as inferred from lineament analysis and near parallelism of the lineament maxima with that of the North Kathiawar Fault and the Chambal Jamnagar Lineament along with the longer axis of the isoseismals of the Bhuj 2001 earthquake indicates a modification in the structural fabric of the region as well as a possibility of development of a major plane of weakness. 相似文献
92.
T. B. Pradeep Kumar Akhileshwar Tiwary Sohail Fahmi 《Journal of the Geological Society of India》2009,73(2):220-228
Mineralisation of uraninite and brannerite occurs in the albitised metasedimentary and intrusive igneous rocks of Kerpura-Tiwari-ka-bas
area in Sikar district, Rajasthan. Samples collected from well dumps contain 0.016 to 1.52% U3O8 with very low ThO2. The host rocks show wide variation in chemical composition due to varying degree of alkali metasomatism, associated alteration
and composition of protoliths. The spatial distribution of uranium in groundwater as well as rock samples from well dumps
indicates localisation of the uranium mineralisation along NNE-SSW and NWSE directions in Kerpura block. Petrographic and
lithogeochemical studies point towards close genetic relationship between alkali metasomatism and uranium mineralisation.
The mineralisation seems to be due to mobilisation of uranium and other LILEs by metasomatising fluids and their deposition
along shear zones at a later stage, which may not be spatially related to zones of intense albitisation. 相似文献
93.
Tectonic controls on the geomorphic evolution of alluvial fans in the Piedmont Zone of Ganga Plain,Uttarakhand, India 总被引:3,自引:0,他引:3
Pradeep K. Goswami Charu C. Pant Shefali Pandey 《Journal of Earth System Science》2009,118(3):245-259
The Piedmont Zone is the least studied part of the Ganga Plain. The northern limit of the Piedmont Zone is defined by the
Himalayan Frontal Thrust (HFT) along which the Himalaya is being thrust over the alluvium of the Ganga Plain. Interpretation
of satellite imagery, Digital Terrain Models (DTMs) and field data has helped in the identification and mapping of various
morphotectonic features in the densely forested and cultivated Piedmont Zone in the Kumaun region of the Uttarakhand state
of India. The Piedmont Zone has formed as a result of coalescing alluvial fans, alluvial aprons and talus deposits. The fans
have differential morphologies and aggradation processes within a common climatic zone and similar litho-tectonic setting
of the catchment area. Morphotectonic analysis reveals that the fan morphologies and aggradation processes in the area are
mainly controlled by the ongoing tectonic activities. Such activities along the HFT and transverse faults have controlled
the accommodation space by causing differential subsidence of the basin, and aggradation processes by causing channel migration,
channel incision and shifting of depocentres. The active tectonic movements have further modified the landscape of the area
in the form of tilted alluvial fan, gravel ridges, terraces and uplifted gravels. 相似文献
94.
Manish Kumar Jha A. K. Verma Pradeep Kumar Gautam Anil Negi 《Journal of the Geological Society of India》2017,90(3):267-272
Shale is an important rock due to its suitability for different engineering and scientific applications. Elevated temperature may cause major deformation or damage in shale rock and it may be of irreversible in nature. Such damage have adverse effect on the physicomechnical properties of shale rock. The uniaxial compressive strength and tensile strength of two shales (upper Vindhyan basin, India) have been estimated at elevated temperature using point load strength index method. The rock samples have been analyzed at various temperatures starting from room temperature to 900 °C. The effect of elevated temperature on the physicomechanical properties and their influence on the uniaxial compressive strength has been studied in detail. Damage induced, in both shale have been estimated using compressional wave velocity. The analysis of the experimental result shows that the uniaxial compressive strength decreases from 63.45 to 18.45 MPa and 60.94 to 22.22 MPa, for Jhiri and Ganurgarh shale respectively. Tensile strength of shales have been also estimated. The value of tensile strength decreases from 3.65 to 1.05 MPa and 3.46 to 1.26 MPa respectively for Jhiri and Ganurgarh shale. Multivariate regression analysis has been carried out to obtain the correlation between physicomechanical properties and uniaxial compressive strength of Jhiri and Ganurgarh shale. 相似文献
95.
Sanjeev Anand Sahu Soniya Chaudhary Pradeep Kumar Saroj Amares Chattopadhyay 《Arabian Journal of Geosciences》2017,10(5):120
The study of surface waves (Rayleigh wave) finds their virtuous applications in a numerous geological and geophysical fields including water, oil, gas, and other subsurface geological probing and exploration. The present paper efforts to investigate the influence of initial stress, Earth magnetism, and gravity on propagation of Rayleigh waves. Considered model is consist of a liquid layer lying over a magnetoelastic orthotropic half-space under self-weight and initial stress. Method of separation of variable is used to solve the equation of motion. Solutions of governing equations are obtained in terms of displacement. Frequency relation for Rayleigh wave has been obtained and matched with classical Rayleigh wave equation. In addition to classical case, some existing results have been deduced as particular case of the present study. Obtained results have been shown through numerical illustrations. It is found that the considered parameters (initial stress, Earth magnetism, and gravity) have prominent effect on phase velocity of Rayleigh wave. Graphical representations have been made to exhibit the velocity profile of Rayleigh waves for different cases with the help of MATHEMATICA. The present study may be useful for seismologists and engineers who are concern with applications of wave propagation in magnetoelastic orthotropic medium. 相似文献
96.
Analyzing projected changes and trends of temperature and precipitation in the southern USA from 16 downscaled global climate models 总被引:1,自引:0,他引:1
Lu Liu Yang Hong James E. Hocker Mark A. Shafer Lynne M. Carter Jonathan J. Gourley Christopher N. Bednarczyk Bin Yong Pradeep Adhikari 《Theoretical and Applied Climatology》2012,109(3-4):345-360
This study aims to examine how future climate, temperature and precipitation specifically, are expected to change under the A2, A1B, and B1 emission scenarios over the six states that make up the Southern Climate Impacts Planning Program (SCIPP): Oklahoma, Texas, Arkansas, Louisiana, Tennessee, and Mississippi. SCIPP is a member of the National Oceanic and Atmospheric Administration-funded Regional Integrated Sciences and Assessments network, a program which aims to better connect climate-related scientific research with in-the-field decision-making processes. The results of the study found that the average temperature over the study area is anticipated to increase by 1.7°C to 2.4°C in the twenty-first century based on the different emission scenarios with a rate of change that is more pronounced during the second half of the century. Summer and fall seasons are projected to have more significant temperature increases, while the northwestern portions of the region are projected to experience more significant increases than the Gulf coast region. Precipitation projections, conversely, do not exhibit a discernible upward or downward trend. Late twenty-first century exhibits slightly more precipitation than the early century, based on the A1B and B1 scenario, and fall and winter are projected to become wetter than the late twentieth century as a whole. Climate changes on the city level show that greater warming will happened in inland cities such as Oklahoma City and El Paso, and heavier precipitation in Nashville. These changes have profound implications for local water resources management as well as broader regional decision making. These results represent an initial phase of a broader study that is being undertaken to assist SCIPP regional and local water planning efforts in an effort to more closely link climate modeling to longer-term water resources management and to continue assessing climate change impacts on regional hazards management in the South. 相似文献
97.
V. Sivakumar Binay Kumar Sandeep Kumar Srivastava B. Gopala Krishna Pradeep Kumar Srivastava A. S. Kiran Kumar 《Journal of the Indian Society of Remote Sensing》2012,40(4):551-564
Digital Elevation Model (DEM) is an important prerequisite for understanding the lunar surface. However, making accurate DEM is a very challenging task due to (a) lack of support of projection parameters in COTS packages (eg. PCI Geomatica), which are to be used in generation of Lunar DEM and (b) unavailability of Ground Control Points (GCPs). In the present study, DEM generation of lunar surface was attempted without GCPs using Rational Function (RF) model from Chandrayaan-1 TMC triplet images. In the study, a good correlation (of almost same order) is observed between Nadir-Fore (NF), Nadir - Aft (NA), Fore - Aft (FA) and Fore - Nadir - Aft (FNA) image pairs. The results suggest that DEM for lunar surface can be created without GCPs using RF model. 相似文献
98.
Balzs M. Fekete John J. Gibson Pradeep Aggarwal Charles J. Vrsmarty 《Journal of Hydrology》2006,330(3-4):444-456
Isotope tracers are widely used to study hydrological processes in small catchments, but their use in continental-scale hydrological modeling has been limited. This paper describes the development of an isotope-enabled global water balance and transport model (iWBM/WTM) capable of simulating key hydrological processes and associated isotopic responses at the large scale. Simulations and comparisons of isotopic signals in precipitation and river discharge from available datasets, particularly the IAEA GNIP global precipitation climatology and the USGS river isotope dataset spanning the contiguous United States, as well as selected predictions of isotopic response in yet unmonitored areas illustrate the potential for isotopes to be applied as a diagnostic tool in water cycle model development. Various realistic and synthetic forcings of the global hydrologic and isotopic signals are discussed. The test runs demonstrate that the primary control on isotope composition of river discharge is the isotope composition of precipitation, with land surface characteristics and precipitation-amount having less impact. Despite limited availability of river isotope data at present, the application of realistic climatic and isotopic inputs in the model also provides a better understanding of the global distribution of isotopic variations in evapotranspiration and runoff, and reveals a plausible approach for constraining the partitioning of surface and subsurface runoff and the size and variability of the effective groundwater pool at the macro-scale. 相似文献
99.
Shallow groundwater in a middle mountain catchment of Nepal: quantity and quality issues 总被引:1,自引:0,他引:1
Bhawani S. Dongol Juerg Merz Monika Schaffner Gopal Nakarmi Pravakar B. Shah Smita K. Shrestha Pradeep M. Dangol Madhav P. Dhakal 《Environmental Geology》2005,49(2):219-229
The use of shallow groundwater in middle mountain catchments of Nepal is a recent development. It was only in early 1998 that a number of dug wells had been constructed in the Jhikhu Khola catchment. But their numbers are rapidly increasing. While it seems to be a good way of accessing additional water resources both for domestic (current) and agricultural purposes (future), it is very important that the groundwater resources are not overexploited. Current dug wells are used to abstract groundwater, which is seasonally being recharged by the abundant monsoon rainfall. The water levels responded rapidly to the rainfall and differed according to the location of the well. The water quality parameters indicated that the water of most of the wells was not suitable for drinking purposes without prior treatment. Microbiological contamination is of particular concern, in addition to the high nitrate and phosphate levels. Some wells show elevated turbidity levels, indicating that there is an interaction between the muddy surface water and the water in the well. 相似文献
100.
This study applies the Ricardian technique to estimate the effect of climate change on the smallholder agriculture sector
in Sri Lanka. The main contribution of the paper is the use of household-level data to analyze long-term climate impacts on
farm profitability. Household-level data allows us to control for a host of factors such as human and physical capital available
to farmers as well as adaptation mechanisms at the farm level. We find that non-climate variables explain about half the variation
in net revenues. However, our results suggest that climate change will have a significant impact on smallholder profitability.
In particular, reductions in precipitation during key agricultural months can be devastating. At the national level, a change
in net revenues of between −23% and +22% is likely depending on the climate change scenario simulated. These impacts will
vary considerably across geographic areas from losses of 67% to gains that more than double current net revenues. The largest
adverse impacts are anticipated in the dry zones of the North Central region and the dry zones of the South Eastern regions
of Sri Lanka. On the other hand, the intermediate and wet zones are likely to benefit, mostly due to the predicted increase
in rainfall. 相似文献