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排序方式: 共有197条查询结果,搜索用时 15 毫秒
191.
Olga Erteleva Felix Aptikaev Saurabh Baruah Santanu Baruah Sajal K. Deb J. R. Kayal 《Natural Hazards》2014,70(1):733-753
Strong ground motion parameters for the Guwahati city area, the capital city of the state of Assam in northeast India, are examined with the help of data accrued from local as well as worldwide network. Empirical relations are proposed for the ground motion parameters as a function of earthquake magnitude, distance, fault type, source depth and velocity characteristics of medium. Seismotectonics of the study region is examined, and a maximum credible earthquake M S ~ 8.0 is presumed from the Brahmaputra fault, the nearest source zone in the city area. Such great/major event may cause intensity of the of 9.3 with a probability of 0,95 in the Guwahati city during time interval of 500 years. Further, the design spectrum with 67 % confidence level and the synthetic three-component accelerograms are constructed. These results are much relevant and useful for structural engineering to mitigate seismic hazards in the region. 相似文献
192.
A grain size model for role of tectonics and climate on sedimentation in Siwaliks in Mohand area 总被引:1,自引:0,他引:1
The physical characteristics of sedimentary record are governed largely by grain size distribution in Mohand area where Middle and Upper Siwalik successions are investigated to characterize the sediments deposited in response to the prevailing tectonic activities and climatic conditions. Here we show with the help of cluster analysis that precipitation and tectonic perturbations generate characteristic patterns of grain sizes and stratigraphic succession. Previous studies suggested an increase in precipitation represented by the abrupt accumulation of sediments to foreland Siwalik basin around 11 to 10 Ma. First appearance of diagnostic minerals of the Great Himalayan complex in Siwalik sediments at 9.2 Ma implies the accelerated erosion of Himalaya during Middle to Late Miocene. The response of sedimentation to tectonic activity is resulted by the presence of coarse grained gravel units in Siwalik succession of Mohand area. Apatite fission-track dates and muscovite cooling ages confirm the strong activity on boundary thrusts during 8-6 Ma. Although the responses are non-linear and transient, we clusterize these non-linear responses to tectonics and climate and quantify them to find out the role of tectonics and climate in architecture of sedimentary succession. 相似文献
193.
Uday Narayan Ghosh Deb Kumar Ghosh Prasanta Chatterjee Mustapha Bacha Mouloud Tribeche 《Astrophysics and Space Science》2013,343(1):265-272
The properties of nonplanar (cylindrical and spherical) ion-acoustic solitary waves (IA SWs) in an unmagnetized, collisionless electron-positron-ion (e-p-i) plasma, whose constituents are q-distributed electrons and positrons and inertial ions, are investigated by deriving the modified Gardner (MG) equation. The well known reductive perturbation method is employed to derive the MG equation. The basic features of nonplanar IA Gardner solitons (GSs) are discussed. It is found that the properties of nonplanar IA GSs (rarefactive and compressive) are significantly affected by the particle nonextensivity. 相似文献
194.
G. Mukhopadhyay S. K. Mukhopadhyay Manas Roychowdhury P. K. Parui 《Journal of the Geological Society of India》2010,76(3):251-266
Gondwana Basins of India occur within the suture zones of Precambrian cratonic blocks of Peninsular India along some linear
belts. More than 99% of the total coal resource of the country is present within these basins. The basins are demarcated by
boundary faults having graben or half-graben geometry. 相似文献
195.
The paper discusses the concept and methodologies for the development of longwall face stability index (LFSI). LFSI is used
for estimation of chock-shield pressure and face convergence. The index comprises of engineering properties of main roof,
depth of mining, different support capacities and mechanical properties of coal seam being mined and provides a numerical
value in the range of −6.17 to 8.13. In this study, 324 finite element models of longwall panel are developed based on various
combinations of geomining conditions of Indian coal measure strata. The LFSI is an outcome of the results from finite element
models. This paper illustrates a real life example for the estimation of chock shield pressure and face convergence based
on LFSI. Validation of the LFSI based calculation is carried out with the field monitored data and found that the LFSI based
approach is sufficient to forecast face stability parameters at longwall face. 相似文献
196.
Arun Chakraborty H. C. Upadhyaya O. P. Sharma Divya Jaisawal S. K. Deb 《Meteorology and Atmospheric Physics》2003,83(3-4):197-220
Summary ?A three-dimensional Ocean General Circulation Model has been developed in stretched coordinate from scratch. The same model
has been used to perform some numerical experiments to simulate the basic circulation pattern and the model variability to
atmospheric forcing. For numerical simulations 72 × 25 grid points in the horizontal directions and nine (10, 30, 75, 250,
500, 1000, 1500, 2000 and 3000 m) vertical levels are considered. The lateral boundaries are set at 60° N and 60° S. The basic
focus of the paper is on the demonstration of the performance of the model and its assessment by employing appropriate forcing
from the outputs of an atmospheric general circulation model. Hence, the model was forced with the forcing (wind and thermodynamic)
derived from the ECMWF runs from the AMIP archives. The preliminary results show the realistic simulation of basic pattern
of different fields. The model simulations show that the model is able to reproduce some of the general features of the ocean,
such as surface currents, surface temperature and salinity, mass transport and meridional heat transport. It is also to be
noted that the model is capable to capture the El-Ni?o and La-Ni?a type events.
Received April 3, 2002; revised June 6, 2002; accepted July 24, 2002
Published online: February 20, 2003 相似文献
197.
The rocks within the Singhbhum shear zone in the North Singhbhum fold belt, eastern India, form a tectonic melange comprising
granitic mylonite, quartz-mica phyllonite, quartz-tourmaline rock and deformed volcanic and volcaniclastic rocks. The granitic
rocks show a textural gradation from the least-deformed variety having coarse-to medium-grained granitoid texture through
augen-bearing protomylonite and mylonite to ultramylonite. Both type I and type II S-C mylonites are present. The most intensely
deformed varieties include ultramylonite. The phyllosilicate-bearing supracrustal rocks are converted to phyllonites. The
different minerals exhibit a variety of crystal plastic deformation features. Generation of successive sets of mylonitic foliation,
folding of the earlier sets and their truncation by the later ones results from the progressive shearing movement. The shear
sense indicators suggest a thrust-type deformation. The microstructural and textural evolution of the rocks took place in
an environment of relatively low temperature, dislocation creep accompanied by dynamic recovery and dynamic recrystallization
being the principal deformation mechanisms. Palaeostress estimation suggests a flow stress within the range of 50–190 MPa
during mylonitization. 相似文献