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801.
The Biot linearized theory of fluid saturated porous materials is used to study the plane strain deformation of a two-phase
medium consisting of a homogeneous, isotropic, poroelastic half-space in welded contact with a homogeneous, isotropic, perfectly
elastic half-space caused by a two-dimensional source in the elastic half-space. The integral expressions for the displacements
and stresses in the two half-spaces in welded contact are obtained from the corresponding expressions for an unbounded elastic
medium by applying suitable boundary conditions at the interface. The case of a long dip-slip fault is discussed in detail.
The integrals for this source are solved analytically for two limiting cases: (i) undrained conditions in the high frequency
limit, and (ii) steady state drained conditions as the frequency approaches zero. It has been verified that the solution for
the drained case (ω → 0) coincides with the known elastic solution. The drained and undrained displacements and stresses are compared graphically.
Diffusion of the pore pressure with time is also studied. 相似文献
802.
Earthquakes cause a variety of hydrological phenomena, including changes in the ground water levels in bore wells. The Koyna
region in the peninsular shield of India, hitherto considered stable in terms of seismic activity, has been active since 1967.
More recently, the earthquakes have been localized to the newly impounded Warna reservoir, which is located south of Koyna,
where a burst of seismicity occurred in 1993. The region continues to remain seismically active even after four decades. Twenty-one
bore wells were drilled around the seismic source volume in the region to observe water level changes resulting from earthquake
phenomena. Our studies have shown coseismic anomalous water level changes to be associated with the moderate earthquakes of
April 25, 1997 and February 11, 1998. Our results show that changes in the ground water level in bore wells are correlated
with micro-earthquake activity, both preceding and following moderately sized earthquakes. The results have implications in
enhancing our understanding of earthquake mechanisms. 相似文献
803.
There are large tracts of wastelands in India, which have been lying almost barren for decades. Wasteland afforestation is found to be a financially viable and environmentally sound use of most of those lands. In addition, tree planting on wastelands is emerging as a potent tool for arresting the increasing misuse and over-exploitation of these lands and environmental degradation in India. This paper presents an overview of afforestation programmes in India undertaken by various agencies, then examines the prospects of increasing the pace of afforestation and identifies various policy and institutional issues that impede the pace of wastelands afforestation. This is done by adopting a two-pronged methodology comprising a review of literature available on the subject (a macro-perspective) and case studies (a micro-perspective). The results of this study show that there is inadequate investment in the forestry sector as a whole and there are several policy and institutional obstacles to promoting wastelands afforestation in India. 相似文献
804.
Recent research has shown evidence of strong coupling between the atmosphere and lithosphere in coastal regions, associating abnormal atmospheric phenomena to the occurrence of strong earthquakes. Surface latent heat flux (SLHF), total column water vapor (CWV), relative humidity (RH) and total ozone column (TOC), analyzed over the epicentral region of the Denali fault earthquake of November 3, 2002, exhibit anomalous behavior that could be related to the earthquake preparatory process and its occurrence. The complementary nature of the parameters provides strong support that the anomalous values were driven by lithospheric processes, rather than other atmospheric phenomena. Due to the wide availability of remote sensing observations of atmospheric parameters, the detection of anomalies can be used to mitigate the earthquake risks. 相似文献
805.
Application of the time-predictable model in Peninsular India for future seismic hazard assessment 总被引:1,自引:0,他引:1
It has been the belief among Earth scientists that the Peninsular Shield is aseismic, as the region attained stability long
ago. However, the earthquake at Koyna (10 December 1967), Bhadrachalam (13 April 1969), Broach (23 March 1970), Hyderabad
(30 June 1983), Khillari (30 September 1993), Jabalpur (22 May 1997), Gujarat (26 January 2001), and additional ones of smaller
magnitudes, altered this concept. This area has experienced many widely distributed shallow earthquakes, some of them having
large magnitudes. It is now widely accepted that seismic activity still continues with moderate events. Therefore, a need
has arisen to take into consideration recent seismological data to assess the future seismic status of Peninsular India. Earthquake
generation model has been studied to develop the statistical relations with surface wave magnitude (M
S
≥ 4.5). Five seismogenic sources showing clustering of earthquakes and including at least three main shocks of magnitude
4.5 ≤ M
S
≤ 6.5 giving two repeat times, have been identified. It is mainly based on the so-called “regional time-predictable model”.
For the considered region it is observed that the time interval between two consecutive main shocks depends on the preceding
main shock magnitude (M
p
) not on the following main shocks magnitude M
f
suggesting the validity of time predictable model in the region. 相似文献
806.
Shalini Singh 《GeoJournal》2005,64(3):215-223
Assuming the above quote as a true portrayal of pilgrims, this article attempts to describe the prototypical pilgrim from
amongst the wide array of contemporary religious and secular tourists. To achieve this end, two approaches have been adopted.
Firstly, the phenomenon/concept of pilgrimages have been discussed, so to distinguish it from the tourism phenomenon and;
Secondly, the geographical notion of genus loci has been employed to exemplify the fundamental quest for ‘geopiety’ attained
through the unification of the pilgrim’s intrinsic belief with its external location. The second part of the article illustrates
the forgoing through an exploration of Himalayan pilgrimages. This has been achieved with a discussion of the emerging practices
and recent trends in Himalayan pilgrimology. This appraisal alludes to Cohen’s quest for a ‘Theology of Tourism.’ The article
concludes with an examination of a specific genre of contemporary tourists in the Indian Himalayas, who have been identified
as ‘environmental pilgrims.’
相似文献
807.
808.
Considering the presence of electric field parallel to geomagnetic field in the magnetosphere, the problem of wave-particle interaction has been considered. Dispersion equation of whistler mode wave in presence of parallel electric field has been derived. Using the effective dispersion equation, the wave-particle interaction has been reformulated to account for the effect of parallel electric field. Using charged particle energy spectrum and magnetospheric field and plasma models, the flux of electron precipitation has been computed. It is shown that the parallel electric field plays an important role and may work in simultaneity with other processes known for enhancement of electron precipitation. 相似文献
809.
In this paper we show that CP-violation is operating in most cosmic-ray sources such as black holes, active galactic nuclei, supernova remnants, and that this leads to the in-equality of the electron—positron component of cosmic rays.Further implications of this result are also discussed. 相似文献
810.
Simulation technique for whistler mode signal propagating through inhomogeneous plasma using WKB approximation has been developed (Singh, K., Singh, R.P., Ferencz, O.E., 2004. Simulation of whistler mode propagation for low latitude stations. Earth Planet Space 56, 979-987). In the present paper, we have used it for the analysis of recorded signals at low latitudes and estimated the nose frequency, which is not observed on the dynamic spectra. At low latitudes nose frequency is ∼100 kHz or more and therefore it is absent in the dynamic spectra due to attenuation of the signal at higher frequencies. The importance of nose frequency is in determining the exact path of propagation, which is required in probing of ambient medium. It is shown that the method permits to study the nose frequency variation, it can be used to deduce physical parameters as the global electric field. A case study permits to get a reasonable value of the electric field, which up to now could not be done at very low latitude. 相似文献