Cyclicity in early Permian fluviatile Gondwana coal measures: An example from Giridih and Saharjuri basins,Bihar, India

The Karharbari and Barakar coal measures of Giridih and Saharjuri basins of Bihar, eastern India, comprise an interbedded assemblage of sandstone, shale and coal in variable abundance. The lithofacies composition records a progressive decrease in sandstone and enrichment of shale and coal from Karharbari up to Barakar. Application of first-order embedded Markov-chain statistics to subsurface data of Karharbari (52 borehole logs) and Barakar (10 borehole logs) reveals that deposition in both the coal measures followed a Markovian mechanism with variable probability, to yield a sequence of upward transition from sandstone through shale to coal. The repetitive fining-upward cycles are asymmetrical, i.e. sandstone → shale → coal → sandstone in the case of Karharbari, but symmetrical as sandstone → shale → coal → shale in Barakar.The abundance of sandstone and the asymmetrical nature of Karharbari cycles are attributed to abrupt shifting of channel bars in low-sinuosity anabranching streams. By contrast, the subequal amount of sandstone, shale and coal forming symmetrical cycles in the overlying Barakar Formation is due perhaps to a slow and gradual shift of the stream channels over and across the adjacent subenvironments of the flood plain.     

Broach (Gujarat) earthquake of March 23, 1970

Summary An analysis of the seismicity of Broach region, Gujarat (India) has been made. The activity of the network of faults present in this region, perhaps, has been responsible for the present earthquake. Earthquake energy, magnitude and focal depth are connected by a single equation. An empirical relation for focal depth and magnitude has been derived for the area.     

Body-wave wave-form modelling and source parameters for the indochina border earthquakes

Wave-form modelling of body waves has been done to study the seismic source parameters of three earthquakes which occurred on October 21, 1964 (M _b =5.9), September 26, 1966 (M _b =5.8) and March 14, 1967 (M _b =5.8). These events occurred in the Indochina border region where a low-angle thrust fault accommodates motion between the underthrusting Indian plate and overlying Himalaya. The focal depths of all these earthquakes are between 12–37 km. The total range in dip for the three events is 5°–20°. TheT axes are NE-SW directed whereas the strikes of the northward dipping nodal planes are generally parallel to the local structural trend. The total source durations have been found to vary between 5–6 seconds. The average values of seismic moment, fault radius and dislocation are 1.0–11.0×10²⁵ dyne-cm, 7.7–8.4km and 9.4–47.4 cm, respectively whereas stress drop, apparent stress and strain energy are found to be 16–76 bars, 8.2–37.9 bars and 0.1–1.7×10²¹ ergs, respectively. These earthquakes possibly resulted due to the tension caused by the bending of the lithospheric plate into a region of former subduction which is now a zone of thrusting and crustal shortening.     

Elastic-wave scattering in a random medium characterized by the Von Karman correlation function and small-scale inhomogeneities in the lithosphere

A Gaussian correlation function characterizes smoothly heterogeneous media, while real heterogeneities in the Earth are often non-Gaussian in nature. Using the Born approximation, mean square amplitudes of the scattered waves have been derived for an elastic media characterized by the Von Karman correlation function. Heterogeneities with different power laws can be defined by the Von Karman correlation function. The sensitivity of fore- and backscattering to heterogeneities with different scales and properties (that is velocity and impedance) is discussed in this paper. The analytical expression for total scattered energy for the incident P waves is also derived for a random medium having the Von Karman correlation function. We find that at high frequencies, the scattered power of converted waves is a function of frequency. In the case of codawave excitation by local earthquakes, which must be handled by the full elastic-wave theory, we can define any type of inhomogeneity by the Von Karman correlation function. It also supports the idea that the lithosphere might have multiple-scale inhomogeneities.     

The linear stability of libration points of the photogravitational restricted three-body problem when the smaller primary is an oblate spheroid

This paper deals with the stationary solutions of the planar restricted three-body problem when the more massive primary is a source of radiation and the smaller primary is an oblate spheroid with its equatorial plane coincident with the plane of motion. The collinear equilibria have conditional retrograde elliptical periodic orbits around them in the linear sense, while the triangular points have long- or short-periodic retrograde elliptical orbits for the mass parameter 0 < _crit, the critical mass parameter, which decreases with the increase in oblateness and radiation force. Through special choice of initial conditions, retrograde elliptical periodic orbits exist for the case = _crit, whose eccentricity increases with oblateness and decreases with radiation force for non-zero oblateness.     

Unsteady MHD free-convective flow through a porous medium with hall currents

The two-dimensional unsteady free-convective flow through a porous medium bounded by an infinite vertical plate for an incompressible viscous and electrically conducting fluid is considered, when a strong magnetic field is imposed in a direction which is perpendicular to the free stream and makes an angle to the vertical direction. The effects of Hall currents on the flows are studied for various values of .     

Finite-difference analysis of the MHD stokes problem for a vertical plate with Hall and ion-slip currents

An explicit finite-difference method is employed to study the MHD free convection heat generating fluid past an impulsively started vertical infinite plate when a strong magnetic field is applied perpendicular to the plate. The velocity and temperature profiles are shown on graphs and the results are discussed in terms of the non-dimensional parameters _e (Hall parameter), _i (ionslip parameter), (heat source parameter), and Gr (Grashof number).     

Radiometric measurements for pearl millet crop

A simple method for determining leaf area index (LAI), absorbed photosynthetically active radiation (APAR), dry biomass and yield in pearl millet (Pennisetum glaucum (L.) R. Br.) crop from remote sensing data is presented. The dry matter and yield can be simulated with maximum accuracy by normalised difference (ND) data during milking stage using the following models: $$\begin{array}{l} DM = - 435.45 + 786.86ND R^2 = 0.90 \\ Yield = - 95.43 + 180.00ND R^2 = 0.62 \\ \end{array}$$      

LOCAL SCOUR AROUND BRIDGE ABUTMENTS

1 INTRODUCTION The protrusion of a bridge abutment or a spur dike into the main channel creates a disturbance and obstruction to the otherwise equilibrium state of sediment transportation in an alluvial river. The flow accelerates and separates at the upstream face of the abutment as it moves past the obstacle, creating a vortex trail that moves downstream in a direction approximately perpendicular to the structure. The result is that the bed around the structure is eroded locally. The l…     

Analysis of gravity gradients over a thin infinite sheet

Expressions are derived for the horizontal and vertical gradients of the gravity anomaly over a thin dipping sheet of infinite depth extent. The resultant of these two gradients, known as the complex gradient, is also derived and properties of the amplitude and phase responses of the complex gradient are studied. It is shown that the amplitude plot is a symmetric curve whose, shape is independent of the dip (?) of the sheet whereas the phase plot is an antisymmetric curve with an offset value equal to ?-π/2. The depth to top of the sheet is obtained from the amplitude plot. The method is applied on a field example and the results are in good agreement with the results obtained by earlier workers.