Quasi-static deformation of a layered half-space by a long strike-slip fault

Theoretical expressions for the surface displacement and shear stress caused by a long strike-slip dislocation in an elastic layer overlying an elastic half-space are derived and the correspondence principle is used to obtain the quasi-static response when the half-space is Maxwell-viscoelastic. Variation of the surface displacement and shear stress with horizontal distance is studied for various times and vertical extents of the fault. It is seen that the quasi-static response differs significantly from the corresponding elastic response.     

Inversion of gravity and magnetic anomalies over some bodies of simple geometric shape

The general expression for gravity and magnetic anomalies over thin sheets and sloping contacts may be expressed as a polynomial of the formFx ²+C₁Fx+C₂F+C₃x³+C₄x²+C₅x+C₆. The initial parameters of the source are obtained from the coefficientsC ₁, C₂,..., C₆ which may be solved by inverting a 6×6 matrix. The initial parameters are modified by successive iteration process using the difference formula until the root mean square error between the observed and calculated anomalies is a minimum. The regional background which may be in the form of a polynomial is estimated by the computer itself. This method is applied on a number of field anomalies and is found to yield reliable estimates of depth and other parameters of the source.     

On two-dimensional elastic dislocations in a multilayered half-space

The two-dimensional problem of a long displacement dislocation in a multilayered half-space is studied. Both plane strain and antiplane strain cases are considered. The Thomson-Haskell matrix method is used to obtain the static field caused by the dislocation. The source is represented in terms of the jumps at the source level in the depth-dependent factors in the Fourier integral representation of the displacements and stresses due to the source in an infinite medium. Explicit expressions for the surface displacements due to dip-slip and strike-slip faults of arbitrary dip are obtained. The formulation developed is quite convenient for numerical computation.     

The heat-capacity of ilmenite and phase equilibria in the system Fe-T-O

Low temperature adiabatic calorimetry and high temperature differential scanning calorimetry have been used to measure the heat-capacity of ilmenite (FeTiO₃) from 5 to 1000 K. These measurements yield S₂₉₈⁰ = 108.9 J/(mol · K). Calculations from published experimental data on the reduction of ilmenite yield Δ₂₉₈⁰(I1) = ?1153.9 kJ/(mol · K). These new data, combined with available experimental and thermodynamic data for other phases, have been used to calculate phase equilibria in the system Fe-Ti-O. Calculations for the subsystem Ti-O show that extremely low values of $\text{?O}{}_2$ are necessary to stabilize TiO, the mineral hongquiite reported from the Tao district in China. This mineral may not be TiO, and it should be re-examined for substitution of other elements such as N or C. Consideration of solid-solution models for phases in the system Fe-Ti-O allows derivation of a new thermometer/oxybarometer for assemblages of ferropseudobrookite-pseudobrookite_ss and hematite-ilmenite_ss. Preliminary application of this new thermometer/oxybarometer to lunar and terrestrial lavas gives reasonable estimates of oxygen fugacities, but generally yields subsolidus temperatures, suggesting re-equilibration of one or more phases during cooling.     

Air-sea fluxes over the global oceans during the FGGE year

Summary Vertical fluxes of momentum, sensible and latent heat have been estimated over the surface of the global oceans. A three-dimensional mesh grid 32 longitude points, 17 latitude points and 365 days from December 1, 1978 to November 30, 1979 is used to obtain seasonal and annual mean values of the surface fluxes. The global climatology shows the seasonal variation, the continental influence, the principal ocean currents and the typical middle latitude (30°–50°) and tropical effects (30°S–30°N). The annual mean of latent heat shows greater flux over the subtropical regions (~ 280 W/m²) than in the polar regions (~ 80 W/m²). On the other hand, the annual mean of sensible heat shows greater flux over the polar regions (~ 100 W/m²) than in the tropics (~ 40 W/m²). Time series analyses of the daily estimates of the surface fluxes show greater energy at high frequencies due to the surface effect; however, the low-frequency spectra show relatively high energy at the 30- to 50-day mode, especially for the middle latitude regions. The 30–50 day filtered data for the surface fluxes, presented in time/latitude cross-sections for the middle latitude regions show a westerly wave propagation with wave numberK = 2 and phase speed of the order of 12 degrees/day from June to August over the southern hemisphere at 55°S.

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Zusammenfassung Die vorliegende Studie beschäftigt sich mit der Einschätzung der vertikalen Impuls-Flüsse und der Flüsse von sensibler und latenter Wärme über der gesamten Meeresoberfläche. Ein dreidimensionales Gitter mit 32 × 17 Punkten und Daten von 365 Tagen (von 1. 12. 1978 bis 30. 11. 1979) wird benutzt, um sowohl Jahreszeiten als auch Jahresmittelwerte der Oberflächenflüsse zu erhalten. Die globale Klimatologie zeigt die jahreszeitlichen Schwankungen, den kontinentalen Einfluß, die wichtigsten Meeresströmungen und die typischen Effekte der mittleren Breiten (30°–50°) und der Tropen (30°S–30°N). Das Jahresmittel latenter Wärme weist größere Flüsse über subtropischen Regionen (ca. 280 W/m²) als über polaren Regionen (ca. 80 W/m²) auf, während andererseits das Jahresmittel sensibler Wärme über Polarregionen (ca. 100 W/m²) größere Flüsse als über den Tropen (ca. 40 W/m²) aufweist. Zeitreihen-Analysen der täglichen Schätzwerte von Oberflächenflüssen deuten auf mehr Energie bei hohen Frequenzen aufgrund des Oberflächeneffekts hin; in jedem Fall zeigen die Niederfrequenz-Spektren relativ hohe Energie in den 30 – 50-Tage-Perioden, besonders für mittlere Breiten. Die über einen Zeitraum von 30 – 50 Tagen gesammelten Daten der Oberflächenflüsse dargestellt in Zeit-Breiten-Querschnitten für mittlere Breiten zeigen von Juni bis August über der südlichen Hemisphäre bei 55°S eine Ausbreitung der westlichen Wellen mit der WellenzahlK = 2 und einer Phasengeschwindigkeit im Ausmaß von 12° pro Tag.

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With 7 Figures     

Apparent velocity and azimuths of short period P-Waves recorded at indian WWSSN stations network

Over 200 earthquakes in the distance range 30°–90° and azimuthal range 0°–360°, recorded at Indian WWSSN stations, have been used in the present study. We have treated the four WWSSN recording stations i.e. New Delhi, Poona, Shillong and Kodai-Kanal, as Super Large Aperture Seismic Array (SLASA) Network with New Delhi being its cross-over point. Short period P-wave data as obtained from these stations have been analysed using a least square technique. Slowness and azimuthal anomalies have been computed for all these events. Relative time residuals have also been calculated. A velocity model has been derived on the basis of the slowness and travel-time data. The results do not indicate presence of any triplication in the travel-time curve. Variations in the relative residuals refer to the tectonic features beneath the recording stations. The P-wave velocity increases continuously in the lower mantle region and there is no indication for the presence of any appreciable velocity gradient.     

A case for internal migration policy in India

Migration helps to minimize regional, socioeconomic, and cultural disparities, and is considered to be an integral component of the development process. Migration helps to diffuse development, technology, and innovations from more developed areas or cities to rural or less developed areas. Little attention, however, has been paid to migration policy in India. Most studies on migration in India either describe the patterns of migration or analyze reasons for the moves. This paper discusses why migration takes place, what are the consequences of migration, whether India has a migration policy, whether India needs a migration policy, and what type of policy is required. The development and entrenchment of urban slums in India is related to the country's lack of migration policy. A two-pronged policy on migration is thus proposed which would ensure employment opportunities and an improved standard of living in rural areas, while taking into account the planning of cities and city surroundings. Rural areas and small towns need to be provided with more employment opportunities, financial and technological support to process raw materials, infrastructure for agricultural service centers, better education and other facilities to improve local living standards, and the diffusion of industries from big cities to district headquarters and medium-size towns. Commensurate efforts should be made in urban centers to prevent the future development of slums.     

Heat and mass transfer of an oscillatory flow with Hall current

In the first part of these notes new expressions—simpler than any previously obtained—are presented in integral form for the derivatives of the α _n ⁰ -functions (required for an interpretation of the observed light changes of eclipsing variables) with respect to the fractional radiir _{1, 2} and projected separation δ of their centres in terms of the modified Bessel functionsK _{0, 1} (x) of the second kind; and utilized for establishing new asymptotic formulae for the computation of ‘boundary integrals’ of the formJ _?1 ⁰ ,n(μ). In the second part of this paper, by a resort to bi-polar coordinates, we shall establish a new type of expansions for the α _n ⁰ -functions valid for any type of eclipses, and converging faster than the expansions of the cross-correlation integral of the form (1) for α _n ⁰ that have so far been established.     

A case of commensurability induced by oblateness

In the three-dimensional restricted three-body problem, it is known that there exists a near one-to-one commensurability ratio between the planar angular frequencies (s _{1, 2, 3}) and the corresponding angular frequency (S ₂) in thez-direction at the three collinear equilibria (L _{1, 2, 3}), which is significant for small and practically important values of the mass parameter (). When the more massive primary is treated as an oblate spheroid with its equatorial plane coincident with the plane of motion of the primaries, it is established that oblateness induces a one-to-one commensurability at the exterior pointL ₃ (to the right of the more massive primary) and at the interior pointL ₂ for 01/2 and that atL ₁ no such commensurability exists. However, the values of the oblateness coefficient (A ₁) involved atL ₂ are too high to have any practical significance, while those atL ₃ being small for small values of may be useful for generating periodic orbits of the third kind.