Iterative geophysical tomography

Summary The algorithm of iterative geophysical tomography is presented. The medium is approximated smoothly by means of B-splines. The tww-point problem of ray computation is solved with the aid of paraxial approximation. The parameters of the medium are obtained from the iterative algorithm of minimizing the quadratic form. Two numerical 2-D examples are given.

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u¶rt; au umamuuu mauu. ¶rt;a annuuaa n nu nu -na. ma na aa a nu nu naaua annuauu. aam ¶rt; n a umamu aua uuauauu a¶rt;amu . am nu¶rt; ¶rt;a 2-D u nua.

     

Relation between the field of surface heat flow and the distribution ofP n -wave velocities for continents

Summary The dependence between P_n-wave velocities and the surface heat flow, temperature at the core-mantl boundary and thickness of the Earth's crust for continents (Europe, Asia, North America and Australia) was investigated statistically in connection with the problem of lateral inhomogeneities in the upper mantle. The relations obtained were compared with those determined under laboratory conditions. The conclusion is that temperature and pressure effects may provide additional explanations of the regional variations of P_n-wave velocities observed in most continents.

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auum ¶rt;auu mu n¶rt; a nmu uua(P_n ), nm mn nm, mnam a u m mum a u¶rt;aa u n uuuma ¶rt;¶rt;m mu P_n. nua ¶rt;a mama aam u¶rt;au nu m n¶rt; amuu u u ¶rt;au u mnam a¶rt;um mmmuu mamau n¶rt;aa am. am ¶rt;, m ua uu m P_n- ¶rt; amu muma n¶rt;m auu m¶rt;uauu u a nmu muua.

     

On the non-tidal secular acceleration of the Earth's rotation

Summary The secular positive acceleration of the Earth's rotation has been computed on the basis of the observed secular decrease of the second zonal harmonic[5]. It corresponds to the observed secular deceleration of the Earth's rotation which should be greater because of oceanic tides.

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¶rt; u a¶rt;a u m aauu [5], u ¶rt;a num u au. m mmmu a¶rt;a u mu au u, m.. n¶rt; n m uu , ¶rt; m n auu nuua.

     

The Earth's structure in the region of the crimea according to the Rayleigh waves observations

Summary The Earth's crust and mantle structure in the region Crimea are investigated on the surface waves observations. For this investigation the long-period seismographs have been installed for the triangle of the seismic stations Simferopol, Alushta, Theodosiya. The phase velocities dispersion has been determined on the base of surface waves for the 8 earthquakes. The observed dispersion curves agree with the theoretical ones for the Earth's model with the crust's thickness of 36–40 km and with (in the mantle) the low velocity layer (V _s =4.3 km/sec at the depth of about 120 km). . , , . 8 . 36–40 . (V _s=4.3 /) 120 .Presented to the IASPEI General Assembly, Madrid, 1969.     

Consequences of transducer inductance for seismograph calibration

Summary The magnification achieved with the standard sine-wave method using seismometers with the calibration and signal coils tightly wound on the same coil former can be erroneous at high frequencies due to the mutual inductance between both coils. An attempt was made to eliminate this influence from the calibration data. The application of theoretical equations was tested with a short-period digital seismograph.

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ma¶rt;ama auau aa nu ¶rt;uu ¶rt;uu maauu m m m a u amma ua u a au u¶rt;mumu ¶rt; ua u auau am, u u a¶rt;m n¶rt;m umu. a ¶rt;aa nnma muam auau ¶rt;a. uu mmuu au u¶rt;a nu auauu mnu¶rt;u aa u anu.

     

Approximate solutions of the surface mass loading of a spherical Earth model

Summary Simple linear representation of the components of an approximate plane solution of point mass loading of the Earth's surface in a conveniently chosen coordinate system leads to selection of a 2nd-degree curve which is the best fit of the spherical solution for the given Earth model. The new approximate solution, which, analogously to the plane solution, can be called a parabolic solution, enables the simple input parameters of the plane solution to be used also for substantially larger angular distances. The comparison with the spherical solution is carried out by computing the effects of the M₂-wave of ocean tides. The results of the computations for the tidal station Brussels prove the two solutions to be in sufficient agreement for global problems as well.

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m nu uau aa nuuum nm u m m au nmu u n¶rt;¶rt; um ¶rt;uam ¶rt;m ma u m mnu, ma auu a n¶rt;¶rt;um u u ¶rt; ¶rt;a ¶rt;u u. nuuum u, m n aauu nm u aam naauu u, nm unam nm ¶rt; ¶rt;a nm u ¶rt;a ¶rt; m u amu. au uu u m uu uu ₂ u nuu. mam uu ¶rt; nuu mauu ¶rt;aam ¶rt;mum au u u ¶rt;a ¶rt;a a¶rt;a.

     

The gravitational effect of bodies with variable density

Summary Determination of the gravitational effect of some bodies, the density of which is supposed to be variable in the vertical direction, possibly in the horizontal direction, too.

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n¶rt;uaumau ma m m, nmm m um mua uu muma anau.

     

Electrical conductivity of some rocks from the Indian subcontinent

Summary Results on electrical conductivity, chemical analysis and age of the rock samples from the Indian Subcontinent are presented. The old Precambrian Indian rocks tend to be less conductive than characteristic rocks of crustal and upper mantle structures.

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nuam mam uu mnm¶rt;mu, uu aaua u n¶rt;u u uu n¶rt; u ¶rt;uu. ma nauu n¶rt; u ¶rt;uu naam mn¶rt;m aamumuu n¶rt; u amuu.

     

Spectra and polarization characteristics of geomagneticPc4 pulsations recorded at field station štrkovec

ama nm u nmam nuau aamumuuaum nau muna Pc4 n ¶rt;a u mauu m, a¶rt; a m m anam ¶rt;u amu u¶rt;a umu. n¶rt;a auum nu¶rt;a u anum¶rt; nau u u nuau aamumu mu ¶rt; u m aum amumu, u au uu m¶rt; naam. mam auam mamau amu nau Pc3 u Pi2 n ¶rt;a u mau ¶rt; u u.     

Some results of the comparison of Courvoisier,Schulze and Yanishevsky balancemeters

Summary Courvoisier, Schulze andYanishevsky type balancemeters have been compared in field exposure under different weather conditions and in the laboratory. Special attention has been devoted to the selectivity and the temperature regime of the detectors. The installation of the instruments is described and the main results of simultaneous measurements with the above-mentioned balancemeters are presented. , . v . .     

The optimal shape design method applied to modelling thermal thinning of the oceanic lithosphere near hot spots

Summary Using the optimal shape design method, which is generally described, and von Herzen's et al. measurements of the heat flow, the shape of the lithosphere and its thermal field is computed in the vertical plane parallel to the hot spot source versus the plate velocity at a distance of about 250 km from the axis of the Hawaiian Island chain. The results are compared with the computations based on Crough's idea of thermal rejuvenation of the oceanic lithosphere above a hot spot source. If we assume that the lateral cross-section of the lithospheric bottom is described by the Gaussian curve h=h₀ exp (–y²/2²), we obtain h₀35 km and 130 km, where h is the value of lithospheric thinning and y the lateral coordinate. We thus obtain the lower limit of the lateral dimension of the Hawaiian anomaly.

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u m¶rt; nmua nua amu, m u ma nuam, u ¶rt;a mn nm, ua a um u mn n mua nmu, naa mu um mum umua mu u ¶rt;a nuuum 250 m uuuaa aunaa. mam a uuu, au a u¶rt;u aa (Crough), aauu mn mu au um a¶rt; umu mu. u n¶rt;num, m ama nn u umu ¶rt;a nuam u aa h=h₀ exp (–y²/2²), m num h₀ 35 u 130 ,¶rt; h—umu mu u —amaa ¶rt;uama. ¶rt;am, =130 m u n¶rt; ama aaaa aauu.

     

Motion of particles in turbulent flow: Hyperbolicity,strange attractors and dynamic stochasticity of a system

¶rt;naa, m ma um uu maunuu m am muu ¶rt;uauu um. nua a mau ammama a, n¶rt; mnu ma u u au uu u¶rt;mu.     

Curvature of a group of difeomorphisms and the instability of Kármán's vortex street

a auu uu nmama uau u¶rt;a u¶rt;mu (nn ¶rt;uu au m a) ua na ááa m a muau¶rt;¶rt;uaua uma. mumu mmmm uu aa nu¶rt;umu n au uu ma a u ma mu.     

Analysis and optimization of wide-band force-balance seismometer responses

¶rt; aau n¶rt;am uu, umu,au mummu u ¶rt;uau ¶rt;uanaa mu um. am n a nmua amm aamumuu um ¶rt; au uu nuu. ¶rt;ma ummuu m¶rt; nmuau mu um a a¶rt;a an¶rt;u n n¶rt;am uu n nmu.     

The four primary geodetic parameters

Summary The four primary geodetic parameters defining the geodetic reference system are discussed from the point of view of their physical meaning and current estimation of their actual accuracy. The geopotential scale factor has been treated as the primary geodetic parameter defining the Earth's dimensions.

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¶rt;am m nu¶rt;uu naama, n¶rt;u¶rt;u um mumu, mu u uu a u mmu. ama amnmuaa ¶rt;am am nu¶rt;u naama, n¶rt; a u.

     

Travel times of seismic waves propagating to the bohemian massif from the south-west direction

mau x¶rt; u a¶rt;u 8 ¶rt;nu mau ¶rt; uu mu u -ana¶rt; auu naa num mam u u na n, g, Sn u Sg mum ma¶rt;am¶rt;a ¶rt; uu mu. a¶rt;u lam mu aua u umau u mm u a amuu ¶rt; En.     

On the possibilities of horizontal propagation ofPc1 pulsations in the ionosphere

Summary The vertical distribution of the contribution of the energy flux density due to the Alfvén(ordinary) wave, guided by the geomagnetic field(and propagating through the ionosphere to the Earth's surface) in the horizontal direction is demonstrated in the mechanism of the horizontal propagation of the Pc1 signal. The distribution with height is shown of the variations of the polarization characteristics of the propagating wave(e.g. the rotation of the polarization plane, changes in ellipticity, attenuation, etc.), which are the result of coupling in the denser layers of the low ionosphere in which also suitable isotropic(extraordinary) modes are generated. The results obtained using the method described in[4, 13] are demonstrated on a model of the daytime ionosphere under incidence of ordinaryL-modes, frequency f=0.3 Hz, and various meridional angles at the ionosphere.

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auauma anmau uaa Pc1 naa m an¶rt;u ¶rt;u nmmu ma uu uma anauu maum n n¶rt; , anma u nmu. naa m an¶rt;u uu aamumu nuauu anma (nauau nmu nuauu, uu unmumu, amau u m.¶rt;.), m m ¶rt;mu au¶rt;mu na uu u . ¶rt; mum n¶rt;¶rt;u umn() ¶rt;. mam num m¶rt; [4, 13] ¶rt;mua ¶rt;u ¶rt; u nu na¶rt;uu a u L-¶rt; amm f=0,3 n¶rt; au u¶rt;uau au.

     

Deceleration in the Earth's rotation due to the Sun

Summary The estimate of the tidal long-term decrease in the angular velocity of the Earth's rotation due to the Sun is given as –(0.8±0.3)×10 ^–22 rad s ^–2. It was computed on the basis of the observed total long-term decrease in , of the observed tidal deceleration of the Moon and the observed decrease in the second-degree zonal Stokes geopotential harmonic term. Adopting the estimate given, the product of the Love number and the tidal phase lag angle due to the Sun (in degrees) comes out as 0.53±0.20.

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am a z nuuu u z mu au u, az : –(0,8±0,3) 10 ^–22 a¶rt; ^–2 . ¶rt; ua n a¶rt;a u , n a¶rt;a nuu u ¶rt;z ¶rt;uu u n a¶rt;a u mz az znmuaz naama ma. u num n au, m nu¶rt;u ua a a z u ( za¶rt;a) a z nuua a (0,53±0,20).

     

Effects of the IMF pro- and anti-sectors in the winter midlatitude ionosphere

Summary On the basis of the 1966–73 data, the effect of the difference between pro- and anti-sectors of the IMF is found to be negligible in the winter midlatitude (Central Europe) ionosphere contrary to the dominant effect of this difference in the high-latitude ionosphere found earlier.

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a ¶rt;a a 1966–73. u¶rt;m u m amu ¶rt; pro- u anti- mau . na a u ¶rt;um (¶rt; na) u, , a naa a, naum um u.

     

The new radiation chart

Summary Basing on the analysis of the most reliable data concerning the atmospheric absorption of long-wave radiation by water vapour, carbon dioxide and ozone, was obtained the integral transmission function of long-wave radiation by the atmosphere. The results are used for plotting the new radiation chart intended for calculating the thermal radiative fluxes in the atmosphere. Comparison of the results of calculations of thermal radiative fluxes has been carried out according to the new chart as well as by the preceding ones.

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