Active fault mapping: An initiative towards seismic hazard assessment in India     

Mithila Verma  B. K. Bansal 《Journal of the Geological Society of India》2013,82(2):103-106

Identification and characterization of active faults and deciphering their seismic potential are of vital importance in seismic hazard assessment of any region. Seismic vulnerability of India is well known as more than 60 % of its area lies in high hazard zones due to the presence of major active faults in its plate boundaries and continental interiors, which produced large earthquakes in the past and have potential to generate major earthquakes in future. The safety of critical establishments, like Power plants, Refinaries and other lifeline structures is a major concern in these areas and calls for a better characterization of these faults to help mitigate the impact of future earthquakes. The paper provides a brief overview of the work carried out in India on active fault research, its limitations and immediate priorities.  相似文献   

Seismic hazard assessment and mitigation in India: an overview     

Mithila Verma  Brijesh K. Bansal 《International Journal of Earth Sciences》2013,102(5):1203-1218

The Indian subcontinent is characterized by various tectonic units viz., Himalayan collision zone in North, Indo-Burmese arc in north-east, failed rift zones in its interior in Peninsular Indian shield and Andaman Sumatra trench in south-east Indian Territory. During the last about 100 years, the country has witnessed four great and several major earthquakes. Soon after the occurrence of the first great earthquake, the Shillong earthquake (M _w: 8.1) in 1897, efforts were started to assess the seismic hazard in the country. The first such attempt was made by Geological Survey of India in 1898 and since then considerable progress has been made. The current seismic zonation map prepared and published by Bureau of Indian Standards, broadly places seismic risk in different parts of the country in four major zones. However, this map is not sufficient for the assessment of area-specific seismic risks, necessitating detailed seismic zoning, that is, microzonation for earthquake disaster mitigation and management. Recently, seismic microzonation studies are being introduced in India, and the first level seismic microzonation has already been completed for selected urban centres including, Jabalpur, Guwahati, Delhi, Bangalore, Ahmadabad, Dehradun, etc. The maps prepared for these cities are being further refined on larger scales as per the requirements, and a plan has also been firmed up for taking up microzonation of 30 selected cities, which lie in seismic zones V and IV and have a population density of half a million. The paper highlights the efforts made in India so far towards seismic hazard assessment as well as the future road map for such studies.  相似文献   

Effect of excavation stages on stress and pore pressure changes for an underground nuclear repository   总被引：2，自引：0，他引：2  

A. K. Verma  M. S. Saini  T. N. Singh  Avi Dutt  R. K. Bajpai 《Arabian Journal of Geosciences》2013,6(3):635-645

This paper provides a brief overview of evolution of deformations, stresses, and pore pressures due to different excavation stages during construction of an URL. Excavation of a rockmass develops damage zone of finite width around the excavated zone which is associated with changes in permeability and affect the fluid flow mechanism. In this study, a coupled hydromechanical (HM) analysis for a water saturated porous rock mass has been done which is caused by sequential excavation and backfill of vertical disposal pit of an URL. For this purpose, an Atomic Energy of Canada Limited’s in-floor concept for a deep geologic repository suitable for Indian condition has been used. Changes in rock deformations, stresses, strains and mechanically induced pore pressure in an undrained condition, during excavation, as well as those caused by mechanically induced rock deformations after backfill of the disposal pit have been modeled. A three-dimensional finite difference tool FLAC^3D (Itasca Consulting Group Inc. FLAC-3D 1997) has been used for the analysis.  相似文献   

Numerical simulation of fault reactivation phenomenon   总被引：1，自引：0，他引：1  

Abhishek Jain  A. K. Verma  V. Vishal  T. N. Singh 《Arabian Journal of Geosciences》2013,6(9):3293-3302

Two-dimensional finite element method was used for evaluating the effect of orthogonal compression on precursor faults. The tendency of reactivation of precursor faults as thrust or normal was analyzed involving the positions and angles of precursor faults with the stresses, strains and displacements. Twelve cases were taken up with different combinations of precursor fault angles (high, >45° and low, <45°) and fault positions for analysis. Different positions and angles of precursor faults are correlated with stresses, strains, and displacements and are discussed in detail. It is hoped that this would help in understanding the past and the present geodynamics of the earth’s crust.  相似文献   

Error propagation in equations for geochemical modeling of radiogenic isotopes in two-component mixing     

Surendra P. Verma 《Journal of Earth System Science》2000,109(1):79-88

This paper presents error propagation equations for modeling of radiogenic isotopes during mixing of two components or end-members. These equations can be used to estimate errors on an isotopic ratio in the mixture of two components, as a function of the analytical errors or the total errors of geological field sampling and analytical errors. Two typical cases (“Small errors” and “Large errors”) are illustrated for mixing of Sr isotopes. Similar examples can be formulated for the other radiogenic isotopic ratios. Actual isotopic data for sediment and basalt samples from the Cocos plate are also included to further illustrate the use of these equations. The isotopic compositions of the predicted mixtures can be used to constrain the origin of magmas in the central part of the Mexican Volcanic Belt. These examples show the need of high quality experimental data for them to be useful in geochemical modeling of magmatic processes.  相似文献   

Classification of glacial lakes using integrated approach of DFPS technique and gradient analysis using Sentinel 2A data     

Prateek Verma  Sanjay Kumar Ghosh 《国际地球制图》2019,34(10):1075-1088

It is important to identify and locate glacial lakes for assessing any potential hazard. This study presents a combination of semi-automatic method Double-Window Flexible Pace Search (DFPS) and edge detection technique to identify glacial lakes using Sentinel 2A satellite data. Initially, Normalized Difference Water Index (NDWI) has been used to identify water and non-water areas, while DFPS and Edge detection technique has been used to identify an optimum threshold value to distinguish between water and shadow areas. The optimal threshold from DFPS process is 0.21, while threshold value of gradient magnitude using edge detection process is 0.318. The number of glacial lakes identified using the above algorithm is in close agreement with previously published results on glacial lakes in Gangotri glacier using different techniques. Thus, a combination of DFPS and edge detection process has successfully segregated glacial lakes from other features present in Gangotri glacier.  相似文献   

Longitudinal distribution of the hard X-ray bursts on the Sun     

V. K. Verma  M. C. Pande 《Solar physics》1985,99(1-2):285-289

The analysis of 315 hard X-ray bursts (HXR) producing solar flares observed by Hinotori satellite shows that the HXR bursts occur most prominently at 110°, 140°, 290°, and 320° longitude, respectively. These longitudes are not only prolific in producing flares in number but also in producing flares with large photon counts.  相似文献   

Remote Sensing of the Lineament Patterns Associated with the Great Boundary Fault of Rajasthan     

P K Verma 《Journal of the Indian Society of Remote Sensing》1991,19(4):253-262

The present work aims to identify, isolate, map and analyse the lineament patterns associated with the Great Boundary Fault (GBF) using remote sensing techniques and to draw some significant conclusions regarding its tectonogenesis therefrom. The locus of the line separating the two distinct patterns of structural trend lines observed on a structural trend map, prepared from the Landsat images, represents the ground disposition of the GBF. The rose diagram plotted for the lineament orientations of different sectors indicates that the whole area was subjected to a similar stress pattern, yet the intensity of stress in each sector was significantly different from the other. The lineament intersection density map clearly demarcates the areas of folding and faulting associated with the GBF. Tectonic anomalies plotted for the area through lineament analysis represent the signatures of prominent surface and sub-surface tectonic elements. The work presents an example for the study of a Precambrian fault system using remote sensing techniques.  相似文献   

Accumulation of DDT Residues in the Testes of Channa punctatus (Bloch): A Gas Liquid Chromatographic Analysis     

R. S. Shrivastava  R. P. Singh  A. Sharma  D. K. Verma 《洁净——土壤、空气、水》1991,19(2):245-248

Residues of DDT isomers accumulated in the testes of Channa punctatus (BLOCH) were quantitatively estimated by exposing the fish to 2.5 ppm sublethal concentration for 32 days. The study revealed a high accumulation of DDT residues in the testes. The maximum concentration of residues was noted on the 32nd day of the experiment. The DDT isomer accumulated in maximum concentrations was followed by DDE and DDD isomers. The maximum residue concentrations were 0.3221 ppm (DDT), 0.1119 ppm (DDE) and 0.0695 ppm (DDD) on the 32nd day of the experiment. The total DDT residue concentration at the final interval was 0.563 ppm.  相似文献   

Carbon dioxide exchange in a temperate grassland ecosystem   总被引：18，自引：0，他引：18  

Joon Kim  Shashi B. Verma 《Boundary-Layer Meteorology》1990,52(1-2):135-149

Carbon dioxide exchange was measured, using the eddy correlation technique, over a tallgrass prairie in northeastern Kansas, U.S.A., during a six-month period in 1987. The diurnal patterns of daytime and nocturnal CO₂ fluxes are presented on eight selected days. These days were distributed throughout most of the growing season and covered a wide range of meteorological and soil water conditions. The midday CO₂ flux reached a maximum of 1.3 mg m^-2 (ground area) s^-1 during early July and was near zero during the dry period in late July. The dependence of the daytime carbon dioxide exchange on pertinent controlling variables, particularly photosynthetically active radiation, vapor pressure deficit and soil water content is discussed. The nocturnal CO₂ flux (soil plus plant respiration) averaged -0.4 mg m^-2 (ground area) s^-1 during early July and was about -0.2 mg m^-2 s^-1 during the dry period.Published as Paper No. 9061, Journal Series, Agricultural Research Division, University of Nebraska-Lincoln, U.S.A.Research Associate and Professor, respectively.  相似文献