Soil responses near Delhi ridge and adjacent regions in Greater Delhi during incidence of a local earthquake     

H. S. Mandal  P. K. Khan  A. K. Shukla 《Natural Hazards》2014,70(1):93-118

In this study, soil response was carried out for the Greater Delhi region. A folded Proterozoic formation was identified as Delhi ridge, passes through its central part along SSW–NNE direction, and appears to be a main geomorphic feature for the study area. The Delhi ridge is an exposed quartzite rock of about 10–100 m wide and ~25 km long with gentler dipping both toward east and west. We have considered the exposed part as an outcrop side near the ridge axis and the dipping area as rigid base away from the ridge axis for ground motion study during the occurrence of the 25 November 2007 earthquake with magnitude M _L 4.3 (Richter scale) that occurred at Delhi–Haryana State boundary. The degree of shaking was very strong and reported major cracks in the buildings near the epicenter area. We have studied the soil response parameters at the surface level, considering horizontally stratified soil layers above rigid base. The equivalent linear method was used for soil response analysis at 25 sites in Greater Delhi area. The peak amplification factors vary from 3.2 to 5.9 and peak resonance frequency varies from 1.2 to 5.3 Hz. The correlation among the peak amplification factor (A) and frequency (f) was empirically established as A = 0.36f + 3.60. Increasing peak amplification factor was found at sites with increasingly thicker alluvium deposit with lower frequency contains ground motion and vice versa. Seismic zoning map was also reconstructed for peak amplification factors and predominant periods for the study area for the mitigation purposes of earthquake damage. The average shear wave velocity up to 30 m soil depth is also obtained for site classification. The average velocity to 30 m [ $ \overline{{V_{\text{s}} }} (30) $ ] is a widely used parameter for classifying sites for predicting their potentiality to amplify seismic shaking. A lower value [ $ \overline{{V_{\text{s}} }} (30) $ ] thus yields a more conservative estimate of ground motion, which generally increases as $ \overline{{V_{\text{s}} }} (30) $ decreases. Present estimate of $ \overline{{V_{\text{s}} }} (30) $ varies from 315 to 419 m/s. In this study, we have identified two site classes C and D, as per National Earthquake Hazard Reduction Program. The city planner or engineers can directly use these data for site-specific assessment during retrofitting of the existing structure, demolition of the old buildings and design a new structure to avoid major destruction of the buildings due to future earthquake.  相似文献   

Use of remote sensing in characterization and management of Dhamni micro-watershed of Chandrapur district of Maharashtra     

Elvis A. Shukla  Jagdish Prasad  M. S. S. Nagaraju  Rajeev Srivastava  D. L. Kauraw 《Journal of the Indian Society of Remote Sensing》2009,37(1):129-137

Soil resource characterization of Dhamni micro-watershed in Chandrapur district of Maharashtra was carried out using IRS-1D LISS-III data in conjunction with field survey and ancillary data. The study indicates that nearly 84.2 per cent of the total geographical area of the watershed is under cultivation. Forest (mainly degraded) occupy only 4.5 per cent area Whereas wasteland with scrub cover 9.4 per cent area of the watershed. Nine soil series were tentatively identified and mapped as soil series association in to five mapping units. These soils belong to order Inceptisol, Vertisol and Mollisol. Except the soils of wasteland with scrub, other soils are moderately suitable for pigeonpea and soybean and have average to good productivity.  相似文献   

Fall,classification and cosmogenic records of the Sabrum (LL6) chondrite     

S. Ghosh  S. V. S. Murty  P. N. Shukla  A. D. Shukla  R. R. Mahajan  N. Bhandari  N. C. Pant  J. B. Ghosh  S. Shome 《Meteoritics & planetary science》2002,37(3):439-448

Abstract— The petrographic and chemical characteristics of a fresh Indian meteorite fall at Sabrum are described. Its mean mineral composition is defined by olivine (Fa_31.4), orthopyroxene (Fs_25.1,Wo_2.0), clinopyroxene (Wo₄₅En_45.6Fs_9.4) and plagioclase (An_10.6Ab_83.6Or_5.8). The meteorite shows moderate shock features, which indicate that it belongs to the S4 category. Based on mineralogical and chemical criteria the meteorite is classified as an LL6 brecciated veined chondrite. Several cosmogenic radioisotopes (⁴⁶Sc, ⁷Be, ⁵⁴Mn, ²²Na and ²⁶Al), noble gas (He, Ne, Ar, Kr and Xe), nitrogen isotopes, and particle tracks density have been measured. Concentrations of cosmogenic ²¹Ne and ³⁸Ar indicate that its cosmic‐ray exposure age is 24.8 Ma. Small amounts of trapped Kr and Xe, consistent with petrologic class 5/6, are present. The track density in olivines is found to be (1.3 ± 0.3) × 10⁶/cm². Activities of most of the short‐lived isotopes are lower than those expected from solar cycle variation. ²²Na/²⁶Al (1.12 ± 0.02) is found to be significantly anomalous, being ?25% lower than expected from the Climax neutron monitor data. These results indicate that the cosmic‐ray flux during the terminal segment of the meteoroid orbit was low. The activities of ²⁶Al and ⁶⁰Co and the track density indicate small meteoroid size with a radius ?15 cm.  相似文献   

Pancake cyclones and anti-cyclones in the ionosphere     

V. I. Petviashvili  O. A. Pokhotelov  P. K. Shukla  L. Stenflo 《Astrophysics and Space Science》1993,202(2):363-372

The formation of pancake cyclones and anticyclones in the E-region of the Earth's ionosphere is considered. It is shown that the vortices can be maintained by the neutral winds or by chemical reactions including the energy release caused by the triple collisions of atomic oxygen with neutrals. It is found that the variations of the magnetic fields induced by the vortices are not localized and decrease slowly far from the vortex core. They can be easily detected by ground based magnetometers or by facilities on board the low-orbiting satellites.  相似文献   

Electron surfing acceleration in oblique magnetic fields     

M. E. Dieckmann  B. Eliasson  M. Parviainen  P. K. Shukla  A. Ynnerman 《Monthly notices of the Royal Astronomical Society》2006,367(3):865-872

Initially, inhomogeneous plasma jets, ejected by active galactic nuclei and associated with gamma-ray bursts, are thermalized by the formation of internal shocks. Jet subpopulations can hereby collide at Lorentz factors of a few. As the resulting relativistic shock expands into the upstream plasma, a significant fraction of the upstream ions is reflected. These ions, together with downstream ions that leak through the shock, form relativistic beams of ions that outrun the shock. The thermalization of these beams via the two-stream instability is thought to contribute significantly to plasma heating and particle acceleration by the shock. Here, the capability of a two-stream instability to generate relativistic field-aligned and cross-field electron flow, is examined for a magnetized plasma by means of a particle-in-cell (PIC) simulation. The electrons interact with the developing quasi-electrostatic waves and oblique magnetic fields. The simulation results bring forward evidence that such waves, by their non-linear interactions with the plasma, produce a highly relativistic field-aligned electron flow and electron energies, which could contribute to the radio synchrotron emissions from astrophysical jets, to ultrarelativistic leptonic subpopulations propagating with the jet and to the halo particles surrounding the accretion disc of the black hole.  相似文献   

Effect of biochar on desiccation of marine soils under constant and cyclic temperatures     

Puspanathan  Thellen Kumar  Jayawardane  Vihan Shenal  Paul  Suvash Chandra  Ying  Kong Sih  Shukla  Sanjay Kumar  Anggraini  Vivi 《Acta Geotechnica》2022,17(12):5441-5464

Acta Geotechnica - Biochar has recently been gaining increasing attention as a stable and sustainable soil amendment material. However, the effect of biochar amendment on the desiccation behaviour...  相似文献   

General class of Bianchi cosmological models with Λ in creation-field cosmology     

R. Chaubey  A. K. Shukla  Ashutosh Singh  T. Singh 《Astrophysics and Space Science》2014,352(2):839-857

The solutions of Einstein’s equations with cosmological constant (Λ) in the presence of a creation field have been obtained for general class of anisotropic cosmological models. We have obtained the cosmological solutions for two different scenarios of average scale factor. In first case, we have discussed three different types of physically viable cosmological solutions of average scale factor for the general class of Bianchi cosmological models by using a special law for deceleration parameter which is linear in time with a negative slope. In second case, we have discussed another three different forms of cosmological solutions by using the average scale factor in three different scenarios like Intermediate scenario, Logamediate scenario and Emergent scenario. All physical parameters are calculated and discussed in each physical viable cosmological model. We examine the nature of creation field and cosmological constant is dominated the early Universe but they do not survive for long time and finally tends to zero for large cosmic time t. We have also discussed the all energy conditions in each cases.  相似文献   

The general class of Bianchi cosmological models with viscous fluid and particle creation in Brans-Dicke theory     

Raghavendra Chaubey  Anjani Kumar Shukla 《天文和天体物理学研究(英文版)》2014,(5):533-552

This paper deals with the general class of Bianchi cosmological models with bulk viscosity and particle creation described by full causal thermodynamics in Brans-Dicke theory. We discuss three types of average scale-factor solutions for the general class of Bianchi cosmological models by using a special law for the deceler- ation parameter which is linear in time with a negative slope. The exact solutions to the corresponding field equations are obtained in quadrature form and solutions to the Einstein field equations are obtained for three different physically viable cosmologies. All the physical parameters are calculated and discussed in each model.  相似文献   

Parametric coupling between electromagnetic ion-cyclotron and shear Alfvén waves     

P. K. Shukla  L. Stenflo 《Astrophysics and Space Science》1990,166(1):93-97

The nonlinear interaction between finite amplitude electromagnetic ion-cyclotron waves and shear-Alfvén waves is considered. It is shown that this process is governed by three coupled equations. They are here used to study modulational instabilities. The relevance of our investigation to low-frequency electromagnetic fluctuations in space plasmas is pointed out.  相似文献   

Modified electron thermal waves     

P. K. Shukla  M. Y. Yu  N. L. Tsintsadze 《Astrophysics and Space Science》1990,165(1):147-152

The linear and nonlinear properties of the modified electron thermal waves are studied. The waves are of acoustic nature and can exist without significant damping in a two-electron temperature plasma. Nonlinearly, they can form propagating localized regions with depletion of hot electrons. Practical applications of our results to space plasmas are discussed.  相似文献