Topographic Constraints on Deviatoric Stress Field in the Indo-Eurasian Collision Region: Seismo-Tectonic Implications     

Mahesh N. Shrivastava  C. D. Reddy  Sanjay K. Prajapati 《Pure and Applied Geophysics》2013,170(4):515-527

The deviatoric stress field are computed from the inversion of Gravitational Potential Energy (GPE) for the Indo-Eurasian plate collision region including the Himalaya and the Tibet Plateau. The resulting stress pattern in combination with stress and strain rates obtained by inverting, respectively, the focal mechanism solution of large earthquakes and GPS derived plate motions are used to study the nature of the present-day deformations. A narrow belt bordering the Himalayan collision zone from the south is characterized by strong compressive stresses. The variations in stress pattern along this belt coincide with arc-normal ridges extending into the Himalaya and are able to explain arc-parallel segmentation of seismicity. Gravitational collapse seems to play an important role in the southeastern Tibet Plateau. Depth sensitivity of the seismic derived stresses and GPS derived surface strain rates coupled with evidence of arcuate shaped high electrical conductivity favour strong ductile flow around the Eastern Himalaya Syntaxis (EHS) at mid-crustal depth. The deflection of crustal flow indicted by the viscous resistance offered by the rigid Sichuan basin adds to the traction stresses to cause clockwise rotation of the block around EHS.  相似文献   

Tracking CO2 plume migration during geologic sequestration using a probabilistic history matching approach     

Sayantan Bhowmik  Cesar A. Mantilla  Sanjay Srinivasan 《Stochastic Environmental Research and Risk Assessment (SERRA)》2011,25(8):1085-1090

Tracking the migration of the CO₂ plume is essential in order to better manage the operation of geologic sequestration of CO₂. However, the large cost of most monitoring technologies, such as time-lapse seismic, limits their application. We investigated the application of a probabilistic history matching methodology using routine measurements of injection data, which are affected by the presence of large-scale heterogeneities, as an inexpensive alternative to track the migration of CO₂ plume in an aquifer. The approach is demonstrated first through a synthetic example in which the ability to detect the presence of flow barriers was tested. In a second example, we applied our method to the In Salah field, one of the largest geological sequestration projects in the world, where the main direction of high permeability features was inferred. The accuracy and reproducibility of the results show that our approach for assisted history matching is an economic and viable option for plume monitoring during geologic CO₂ sequestration.  相似文献   

Analysis of Circular Elastic Plate Resting on Pasternak Foundation by Strain Energy Approach     

Sanjay Kumar Shukla  Ashish Gupta  Nagaratnam Sivakugan 《Geotechnical and Geological Engineering》2011,29(4):613-618

In this paper, an analytical expression for the deflection of a thin circular elastic plate resting on the Pasternak foundation is derived by adopting the strain energy approach. The parametric study is carried out to observe the location of the plate lift-off and the variation of the deflection profiles for comparing the variation pattern reported in the literature based on an approximate solution technique. It is found that the radial distance of the point of lift-off of the plate decreases with increase in the values of both the shear modulus and the modulus of subgrade reaction of the foundation soil; the reduction being more for their lower values. It is also observed that the variation in deflection of the plate at any radial distance due to change in soil subgrade conditions is significant for lower values of modulus of subgrade reaction.  相似文献   

Snow cover depletion under changed climate with the help of remote sensing and temperature data   总被引：1，自引：1，他引：0  

Sanjay K. Jain  L. N. Thakural  R. D. Singh  A. K. Lohani  S. K. Mishra 《Natural Hazards》2011,58(3):891-904

Snow cover depletion curve (SDC) is one of the important variables in snow hydrological applications, and these curves are very much required for snowmelt runoff modeling in a snowfed catchment. Remote sensing is an important source of snow cover area which is used for preparation of SDC. Snow cover maps produced by Moderate Resolution Imaging Spectroradiometer (MODIS) satellites are one of the best source of satellite-based snow cover area at a regular interval. Therefore, in this study, snow cover maps have been prepared for the years 2000?C2005 using MODIS data. The study area chosen viz. Beas basin up to Pandoh dam falls in western Himalayan region. For snowmelt runoff modeling, catchment is divided into number of elevation zones and SDC is required for each zone. When sufficient satellite data are not available due to cloud cover or due to some other reasons, then SDC can to be generated using temperature data. Under changed climate conditions also, modified SDC is required. Therefore, to have SDC under such situations, a relationship between snow cover area and cumulative mean temperature has been developed for each zone of the catchment. This procedure of having snow cover maps has two main purposes. First, it could potentially be used to generate snow cover maps when cloud-free satellite data are not available. Second, it can be used to generate snow-covered area in a new climate to see the impact of climate change on snowmelt runoff studies.  相似文献   

Intensity map of Mw 6.9 2011 Sikkim–Nepal border earthquake and its relationships with PGA: distance and magnitude     

Prajapati  Sanjay K.  Kumar  Ashok  Chopra  Sumer  Bansal  B. K. 《Natural Hazards》2013,69(3):1781-1801

We compiled available information of damages and other effects caused by the September 18, 2011, Sikkim–Nepal border earthquake from the print and electronic media, and interpreted them to obtain Modified Mercalli Intensity (MMI) at over 142 locations. These values are used to prepare the intensity map of the Sikkim earthquake. The map reveals several interesting features. Within the meizoseismal area, the most heavily damaged villages are concentrated toward the eastern edge of the inferred fault, consistent with eastern directivity. The intensities are amplified significantly in areas located along rivers, within deltas or on coastal alluvium such as mud flats and salt pans. We have also derived empirical relation between MMI and ground motion parameters using least square regression technique and compared it with the available relationships available for other regions of the world. Further, seismic intensity information available for historical earthquakes which have occurred in NE Himalayas along with present intensity has been utilized for developing attenuation relationship for NE India using two-step regression analyses. The derived attenuation relation is useful for assessing damage of a potential future earthquake (earthquake scenario-based planning purposes) for the northeast Himalaya region.

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Temperature of interstellar warm ionized medium     

Sanjay K. Mishra  Mahendra Singh Sodha  Sweta Srivastava 《Astrophysics and Space Science》2013,344(1):193-203

This investigation on the temperature of the interstellar warm ionized medium (WIM) is characterized by the number and energy balance of the constituents of the WIM complex plasma viz. H plasma (electrons/ions/neutral atoms) and graphite dust, having a size distribution, characterized by the MRN (Mathis, Rumpl and Nordsieck) power law. Ionization of neutral atoms, electron–ion recombination, photoemission of electrons from and accretion on the dust and cooling through electron collisional excitation, followed by radiative decay of atoms has been included in the analysis. An appropriate expression for the rate of emission and mean energy of photoelectrons emitted from the surface of positively charged dust particles has been used which takes into account the dependence of absorption efficiency on wavelength of the radiation, radius of the particle and spectral irradiance distribution. The results of the parametric analysis have been displayed graphically. It is seen that the consensus values of temperature, surface potential on the dust particles and electron/ion/neutral atom densities, characteristic of interstellar warm ionized medium can be explained on the basis of plausible combinations of the dust particle density n _d and the parameter f _ex α _ex , where f _ex is the fraction of the energy of the neutral gas atoms which gets irradiated, α _ex n _e n _n is the number of the neutral atoms, which get excited per unit volume per unit time and n _e (n _n ) correspond to the density of electrons (neutral atoms).  相似文献   

Effects of soil layering on the characteristics of basin-edge induced surface waves     

Jay Prakash Narayan  Sanjay Kumar 《Acta Geophysica》2009,57(2):294-310

This paper presents the effects of soil layering on the characteristics of basin-edge induced surface waves and associated strain and aggravation factor. The simulated results revealed surface wave generation near the basin-edge. The first mode of induced Love wave was obtained in models having increasing velocity with depth and a large impedance contrast between the soil layers. Amplitude amplification or de-amplification of body waves was proportional to the impedance contrast between the soil layers. The average aggravation factor was inversely proportional to the impedance contrast between the soil layers in case of increasingvelocity models and proportional in case of decreasing-velocity basinedge models. On the other hand, the maximum strain was inversely proportional to the impedance contrast between the soil layers in both cases. On the average, strain was greater in case of increasing-velocity models but the average aggravation factor was greater in case of decreasingvelocity models.  相似文献   

Geotechnical Behavior of Recycled Copper Slag-Cement-Treated Singapore Marine Clay     

Sanjay Kumar Bharati  Soon Hoe Chew 《Geotechnical and Geological Engineering》2016,34(3):835-845

Copper slag is a by-product obtained from production of copper metal. As copper slag contains silica and alumina, it may exhibit pozzolanic property, and hence it may be re-use in ground improvement applications as a partial replacement of cement. Present study evaluates systematically the possible pozzolanic property of copper slag as well as studies the effect of copper slag on engineering properties of cement-treated clay. X-rays diffraction method was employed to assess the possible pozzolanic property of copper slag. Effect of copper slag on engineering properties (i.e. compressive strength and compressibility) of cement-treated clay was studied with samples prepared with constant water content and workability. The test results showed that with sufficient curing time and at constant workability, the compressive strength of cement-treated clay was found to be increased with increasing amount of copper slag at high cement content but the compressive strength remained the same with increasing amount of copper slag at low cement content. Compressibility of cement-treated clay was found to be unchanged with increasing amount of copper slag. It was concluded that copper slag can be used as partial replacement of cement in treating soft marine clay.  相似文献   

Selection of Suitable Window Size for Speckle Reduction and Deblurring using SOFM in Polarimetric SAR Images     

Sanjay Shitole  Shaunak De  Y. S. Rao  B. Krishna Mohan  Anup Das 《Journal of the Indian Society of Remote Sensing》2015,43(4):739-750

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Pseudo-dynamic approach of seismic active earth pressure behind retaining wall   总被引：4，自引：2，他引：4  

Deepankar Choudhury  Sanjay S. Nimbalkar 《Geotechnical and Geological Engineering》2006,24(5):1103-1113

Knowledge of seismic active earth pressure behind rigid retaining wall is very important in the design of retaining wall in earthquake prone region. Commonly used Mononobe-Okabe method considers pseudo-static approach, which gives the linear distribution of seismic earth pressure in an approximate way. In this paper, the pseudo-dynamic method is used to compute the distribution of seismic active earth pressure on a rigid retaining wall supporting cohesionless backfill in more realistic manner by considering time and phase difference within the backfill. Planar rupture surface is considered in the analysis. Effects of a wide range of parameters like wall friction angle, soil friction angle, shear wave velocity, primary wave velocity and horizontal and vertical seismic accelerations on seismic active earth pressure have been studied. Results are provided in tabular and graphical non-dimensional form with a comparison to pseudo-static method to highlight the realistic non-linearity of seismic active earth pressures distribution.  相似文献