Geospatial contour mapping of shear wave velocity for Mumbai city   总被引：5，自引：3，他引：2  

Sumedh Yamaji Mhaske  Deepankar Choudhury 《Natural Hazards》2011,59(1):317-327

Shear wave velocity is one of the most important input parameter in the analysis of geotechnical earthquake engineering problems, particularly to estimate site-specific amplification factor and ground response study. Dynamic in situ tests such as spectral analysis of surface waves (SASW) or multichannel analysis of surface waves (MASW) are very expensive. Also due to lack of specialized personnel, these tests are generally avoided in many soil investigation programs. Worldwide, several researchers have developed correlations between the SPT ‘N’ value and shear wave velocity ‘V _s’, which are useful for determining the dynamic soil properties. In the present study, more than 400 numbers of soil borehole data were collected from various geotechnical investigation agencies, government engineering institutes and geotechnical laboratories from different parts of Mumbai city, which is financial capital of India with highest population density. In this paper, an attempt has been made to develop the correlation between the SPT ‘N’ value and shear wave velocity ‘V _s’ for various soil profile of Mumbai city and compared with other existing correlations for different cities in India. Using Geographical Information System (GIS), a geospatial contour map of shear wave velocity profile for Mumbai city is prepared with contour intervals of 25 and 50 m/s. The scarcity of database or maps of shear wave velocity profile for Mumbai city will make the present geospatial contour maps extremely useful and beneficial to the designer, practitioners for seismic hazard study involved in geotechnical earthquake engineering.  相似文献   

Equation of state and melting point studies of forsterite     

N. Choudhury  S. L. Chaplot  K. R. Rao 《Physics and Chemistry of Minerals》1989,16(6):599-605

We report in this paper results of lattice dynamical calculations of the thermodynamic properties, namely, the equation of state and the melting point of forsterite. The root mean square displacements of atoms and thermal parameters are also evaluated. It is observed from our results, that, a modified Lindemann criterion for melting may be proposed for an ionic ‘molecular’ solid like forsterite. Agreement among various theoretical and experimental results is satisfactory indicating that lattice dynamical studies based on microscopic quasiharmonic formulations help in understanding the macroscopic properties of forsterite, over a wide range of temperature and pressure.  相似文献   

SOILS: AGRICULTURAL AND ENGINEERING PROPERTIES     

Dulima Jali  Jahangir E. Elahi Choudhury 《Singapore journal of tropical geography》1993,13(1):1-13

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Variations In Upper Mantle Structure Under Northern Australia     

S. C. Dey  B. L. N. Kennett  J. R. Bowman  A. Goody 《Geophysical Journal International》1993,114(2):304-310

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Potential CO<Subscript>2</Subscript> Emission Due to Loss of Above Ground Biomass from the Indian Sundarban Mangroves During the Last Four Decades     

Anirban Akhand  Anirban Mukhopadhyay  Abhra Chanda  Sandip Mukherjee  Abhishek Das  Sourav Das  Sugata Hazra  Debasis Mitra  S. B. Choudhury  K. H. Rao 《Journal of the Indian Society of Remote Sensing》2017,45(1):147-154

Sundarban, the largest single patch of mangrove forest of the world is shared by Bangladesh (~ 60 %) and India (~ 40 %). Loss of mangrove biomass and subsequent potential emission of carbon dioxide is reported from different parts of the world. We estimated the loss of above ground mangrove biomass and subsequent potential emission of carbon dioxide in the Indian part of the Sundarban during the last four decades. The loss of mangrove area has been estimated with the help of remotely sensed data and potential emission of carbon dioxide has been evaluated with the help of published above ground biomass data of Indian Sundarban. Total loss of mangrove area was found to be 107 km² between the year 1975 and 2013. Amongst the total loss ~60 % was washed away in the water by erosion, ~ 23 % was converted into barren lands and the rest were anthropogenically transformed into other landforms. The potential carbon dioxide emission due to the degradation of above ground biomass was estimated to be 1567.98 ± 551.69 Gg during this period, which may account to 64.29 million $ in terms of the social cost of carbon. About three-forth of the total mangrove loss was found in the peripheral islands which are much more prone to erosion. Climate induced changes and anthropogenic land use change could be the major driving force behind this loss of ‘blue carbon’.  相似文献   

Wide-angle linear forward modelling of synthetic seismograms     

A. Dey  A. Gisolf 《Geophysical Prospecting》2007,55(5):707-718

We address the issue of linearity and scale dependence in forward modelling of seismic data from well logs, for large ray parameters, wide angles or large offsets. We present a forward model, within the context of seismic‐to‐well matching, that is linearized in the elastic properties of the earth. This model preserves linearity at large ray parameters and can handle fine‐layering effects such as induced anisotropy. Starting from a low‐contrast small‐ray‐parameter model, we extend it to a large‐ray‐parameter model by fully linearizing the elastic‐property contrasts. Overall linearity of the forward model is extended by partitioning the compressional‐wave and shear‐wave velocity fields into two fundamental scales: a kinematic scale that governs wavefield propagation effects and a dynamic scale that governs wavefield scattering effects. This analysis reveals that the standard practice in forward modelling of strongly filtering the ratio of compressional‐wave velocity to shear‐wave velocity is well founded in the underlying physics. The partitioning of the velocity fields also leads naturally to forward modelling that accounts fully for stretch effects, to resolution of the angle‐of‐incidence versus ray‐parameter dichotomy in seismic‐amplitude analysis, and to full accounting for induced anisotropy and dispersion effects due to fine‐layering of isotropic media. With the onset of routine long‐offset acquisition and the compelling need to optimize asset management in order to maximize reserve recovery, this forward model recognizes the physics of seismic wave propagation and enables a more complete exploitation of amplitude information in pre‐critical seismic data.  相似文献   

Seismic induced soil gas radon anomalies observed at multiparametric geophysical observatory,Tezpur (Eastern Himalaya), India: an appraisal of probable model for earthquake forecasting based on peak of radon anomalies     

Chetia  Timangshu  Baruah  Saurabh  Dey  Chandan  Baruah  Santanu  Sharma  Sangeeta 《Natural Hazards》2022,111(3):3071-3098

Natural Hazards - We applied multiple linear regressions to scrutinize the maximum variability produced in soil gas radon (Rn-222) by pressure, temperature and rainfall. Statistical methodologies...  相似文献   

GIS-based soil liquefaction susceptibility map of Mumbai city for earthquake events     

Sumedh Yamaji Mhaske  Deepankar Choudhury 《Journal of Applied Geophysics》2010,70(3):216-225

The problem of liquefaction of soil during seismic event is one of the important topics in the field of Geotechnical Earthquake Engineering. Liquefaction of soil is generally occurs in loose cohesionless saturated soil when pore water pressure increases suddenly due to induced ground motion and shear strength of soil decreases to zero and leading the structure situated above to undergo a large settlement, or failure. The failures took place due to liquefaction induced soil movement spread over few square km area continuously. Hence this is a problem where spatial variation involves and to represent this spatial variation Geographic Information System (GIS) is very useful in decision making about the area subjected to liquefaction. In this paper, GIS software GRAM++ is used to prepare soil liquefaction susceptibility map for entire Mumbai city in India by marking three zones viz. critically liquefiable soil, moderately liquefiable soil and non liquefiable soil. Extensive field borehole test data for groundwater depth, standard penetration test (SPT) blow counts, dry density, wet density and specific gravity, etc. have been collected from different parts of Mumbai. Simplified procedure of Youd et al. (2001) is used for calculation of factor of safety against soil liquefaction potential. Mumbai city and suburban area are formed by reclaiming lands around seven islands since 1865 till current date and still it is progressing in the area such as Navi Mumbai and beyond Borivali to Mira road suburban area. The factors of safety against soil liquefaction were determined for earthquake moment magnitude ranging from M_w = 5.0 to 7.5. It is found that the areas like Borivali, Malad, Dahisar, Bhandup may prone to liquefaction for earthquake moment magnitude ranging from M_w = 5.0 to 7.5. The liquefaction susceptibility maps were created by using GRAM++ by showing the areas where the factor of safety against the soil liquefaction is less than one. Proposed liquefaction susceptibility map of Mumbai city can be used by researchers for earthquake hazard analysis, for the preventive measures in disaster management, for urban planning and further development of Mumbai city and suburban area.  相似文献   

Interference of an upstream pier on local scour at downstream piers   总被引：1，自引：0，他引：1  

Shivakumar Khaple  Prashanth Reddy Hanmaiahgari  Roberto Gaudio  Subhasish Dey 《Acta Geophysica》2017,65(1):29-46

In this study, three kinds of pier arrangements were tested. They are (i) two piers in tandem, (ii) two piers in staggered arrangement, and (iii) three piers in symmetrically staggered arrangements. In the arrangement of two piers in tandem, the equilibrium scour depth at downstream pier decreases with an increase in downstream distance up to approximately eight times pier diameter and then increases with further increase in downstream distance. However, the scour depth at downstream pier is always smaller than that at upstream pier. In the arrangement of two staggered piers, the scour depth at the downstream pier for L/b = 4, where L is the offset distance and b is the pier diameter, is the same as that of the upstream pier at S = 8b, where S is the streamwise spacing or distance between piers. Further, for three piers in staggered arrangement, as the lateral spacing between downstream piers increases, the equilibrium scour depth at downstream pier decreases.  相似文献   

Probing the dark ages with redshift distribution of gamma-ray bursts     

T. Roy Choudhury  R. Srianand 《Monthly notices of the Royal Astronomical Society》2002,336(2):L27-L31

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