Numerical modelling of time-harmonic seismic wave fields in simple structures by the gaussian beam method. part I

m¶rt;au n unm ¶rt; u ¶rt;uau uu n m nm ¶rt; ¶rt;. a uau ¶rt;m a ma m nau a¶rt;a, amu aa mu. au mu uu naam, m m¶rt;au n ¶rt;am ¶rt;mam m mam ¶rt;a u amu aa mu (. u. 9). aumu amu, uauau n ma nam ¶rt;a . ¶rt; amu m am ¶rt;m ¶rt;am mumm mam a naama am, an. aa uuau n, naama uauau n, um¶rt;.     

Some remarks on the estimation of geothermal topocorrections

Summary The paper deals with some problems connected with the evaluation of the temperature gradient topocorrections for the purposes of the Earth's heat flow measurements. Some errors, occurring in the routine use of the method, suggested by Jeffreys and Bullard (JB method), are discussed. An example of simple topographic features is used to compare this method with the results obtained by a numerical solution of the heat conduction equation (NS method) by means of the finite difference method. The calculations have shown that the NS method is more precise, but its results are very sensitive to the approximation of the surface used. A stepwise approximation of the surface used in a 3-D model of a real mountainous region causes artificial oscillations of the surface values of the topocorrections, and the accuracy of the obtained results is comparable with that of the JB method. Thus, we are faced with the problem of a more appropriate approximation of the relief without the mentioned negative consequences to the superficial values of the topocorrections.

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¶rt;am n, a mnauu ua¶rt;uma mnam nu uu mn nma. u m uu, nu n mu nuu m¶rt;a, m n¶rt; u u a¶rt; (J B m¶rt;). a nu nm mnau mm m¶rt; a u u au mnn¶rt;mu (NS m¶rt;) n n am. uu naau, m NS m¶rt; m JB m¶rt;, m mam u mum annuauu nmu. B a - ¶rt;u ¶rt;mum amu nu¶rt;um mnama annuau u au nm au mnu u mm n mam aua mm JB m¶rt;a. a naa, m n unau num NS m¶rt;a a¶rt; nmu a¶rt; nuuu nmu.

     

Travel times of Friuli earthquakes propagating to the Bohemian Massif

17 mmu u uma uu 1976. anua 5 ¶rt;numu mauumu u¶rt;a mu u m na Pn, Pg, Sn u Sg. u¶rt; numm muam u mum ma¶rt;am¶rt;a ¶rt; uu mmu n¶rt;naam nu m m uamm aumm. ¶rt;am nu m mmu maua.     

Complex of phenomena which arise simultaneously with the generation of microseismic vibrations

Summary The complex of phenomena which arise simultaneously with microseismic vibrations embraces the three spheres of the Earth. In the atmosphere there arise infrasound waves, whereas hydroacoustic and microseismic waves propagate in the water and Earth's crust. In several cases the originating of intensive microseisms is connected with the generation of great and rather great magnetic storms. Such a relation was observed between microseismic vibrations recorded by seismic station Perth (Australia) and magnetic storms recorded by the Irkutsk observatory. When the rate of amplitude and period variations reached a definite value: A/t>0.15 and T/t>0.12, the magnetic storms in Irkutsk arised definitely.Directional radiation characteristic of an area of standing sea waves of limited dimensions into water and air are determined. For radiation into water a sharply directed vertical characteristic is valid. For radiation into atmosphere by coherent sources the directional characteristic is sinusoidal: zero radiation in the normal direction to the sea surface and maximum radiation in the plane of the aquatorium.

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uu , , . , , . . , () , . : />0.15 />0.15, . . . , , : .

     

Deformation properties of the lithosphere derived from data on recent crustal movements of the earth

aamuam a¶rt;aa ¶rt;uu ¶rt; m u¶rt;mu, uau n¶rt; uu mua ¶rt;uu a uau u . a auu au mmuu mam ¶rt;au mua ¶rt;uu ¶rt;am m am ¶rt; ¶rt;au ma um.     

Calculation of particle distribution by the data on spectral transparency

, , . . , , , . , , .Summary A general method for obtain the particle size distribution curve of the dispersed system is developed according to data of its spectral transparency, based onMellin's transformation. The method does not contain any arbitrary suppositions about spectrum character of particles. A simple calculation scheme is supposed, examples of inversion are given, the range of spectrum and the accuracy of transparency measurements necessary to obtain the inversion with a given accuracy are estimated. The calculation scheme is appropriate for every kind of errors of measurement and calculation and contains moderate requirements to their accuracy.     

Geostationary satellites and variations in the position of the Earth's mass center

¶rt;am m unau a¶rt;umaua m nu ma a u mum u au. am a uu u ma a a umaua nmua mmu ¶rt; u mu m uauu.

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Presented at the Meeting SSG 5.49 of the IAG, Uppsala, August 7, 1978.     

Variations in the Earth's rotation and crustal deformations

a mmuu ¶rt; ¶rt;au nm u , a auauu ma mu au u. aamuam m¶rt; a, ma u mua mu ¶rt;au u ¶rt;aa u uma a; m a mu ¶rt;auu m ¶rt;muam 10% m ¶rt;au, a u nuuau m .     

On the structure of the interplanetary magnetic field under non-stationary boundary conditions

Summary The structure of the interplanetary magnetic field (IMF) is investigated theoretically in a kinematic approximation under frozen-in conditions in the solar wind and non-stationary boundary conditions. As an example, a time-dependent model of the IMF, created in the case of a change of the general magnetic field of the Sun represented by the dipole term, is analyzed. Very simple assumptions as to the field of velocities in the solar wind are made. The results show the formation of zero IMF points of two types(O, X). Points of theO-type are formed and move radially in the equatorial plane. They are surrounded by magnetic clouds with loops of lines of force. Points of theX-type are formed and move radially above the poles.

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muu u¶rt;aa mma nam aum n() uamu nuuuu nu uu mu m u mauaau uu. am nua ama ¶rt; , ua nu uuu aum n a, n¶rt;ma ¶rt;un , auu m u. mum n m m ¶rt;a nmu n¶rt;nu. mam naam aau m ¶rt; mun(O, X). uO-muna uam u ¶rt;um a¶rt;ua amua nmu. u aumu aau nmu u uu. uX-muna uam u ¶rt;um a¶rt;ua a¶rt; nau.

     

Diurnal asymmetry of radio wave absorption on anomalous winter days

au uu nu a¶rt;u a amma a nu¶rt; 1966–1981 naa, m ¶rt;, auu m m, u nu u ¶rt; uu n n¶rt;, ¶rt;num nu aa ¶rt; ¶rt;a n n¶rt;. m uu aa ¶rt;u u mu u.     

On the possibility of utilizing grid reports in a local model of short-range forecast of meteorological elements

Summary In the experiment described, we test the possibility of utilizing forecasts of the pressure field, contained in GRID reports, to solve the problem of horizontal boundary conditions of a local model of short-range forecast of meteorological elements. We prove that the assumption of a linear tendency of the prognostic variables in the boundary region yields good results, using the Perkey-Kreitzberg method[1], even if applied to period T=24 hrs. In the Perkey-Kreitzberg method the effect of the horizontal diffusion in the boundary region is suppressed[2]. However, considering the diffusive term apart from the procedure of the method mentioned proves detrimental to the forecast.

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nua num n m unau n n ¶rt;au, ¶rt;au ¶rt; ¶rt; u numaau u a ¶rt;u am na muu m. aam, m n¶rt;nu u m¶rt;uu nmuu n au amu nu unauu m¶rt;a u- [1] ¶rt;am u mam ¶rt;a nu nuuu nu¶rt; T=24 a. m¶rt; u- nu¶rt;um n¶rt;au uuuma ¶rt;uuu au amu[2]. ama ¶rt;u a n¶rt; nu¶rt; m¶rt;a nu¶rt;um, ¶rt;a, ¶rt;u n.

     

Stresses and displacements due to a stationary point source of heat in an elastic halfspace

am amu ¶rt; ¶rt; mnu annu u u, a maua m umu mna n nnmam. a auu uu naa, m uau anu m anuu amua muna u am am u n ummamuu anu uu nmu nnmama. auum m¶rt;uauu ¶rt;mu ¶rt;mu mau anu, ammu: a) ¶rt;mu um numa amu umua mna; ) m uu uu nm aa u u u nu uuu aa nuu a nmu u; ) aau amuau anu ammuu aau, m m nm u¶rt; n u amumu um mu am.     

Long-period fluctuations observed in the ionospheric absorption variations

Summary By subsequent application of power spectrum analysis, autocorrelation analysis and fast Fourier transform (FFT) of the day- and night-time absorption values of five LF radio-paths (164 kHz, 155 kHz, 185 kHz, 218 kHz and 272 kHz) in Europe during the interval 1 June 1979–30 June 1980, fluctuations with the following basic (fundamental), commonly recurrent periods were found: 3.5–5 days and 10.5–12 days. They exist in all investigated time series, while 6- and 9-day fluctuations are observed on the northern radio-paths (185 kHz and 272 kHz). Shorterperiod oscillations are most active during autumn and especially during winter, while the longerperiod oscillation (10.5–12-day) has significant amplitudes also in summer.

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n n¶rt;am nuu aaua nma mu, amu aaua u m maauu () ¶rt; u ¶rt;a n nu u nmu a¶rt;u ma (164 , 155 , 185 , 218 u 272 ) a¶rt; n nu¶rt; 1 u 1979–30 u 1980. u a¶rt; ¶rt;u (¶rt;ama) nmu nu¶rt;: 3.5–5 ¶rt; u 10.5–12 ¶rt. u nummm u¶rt;a ¶rt;a. 6- u 9-m au a¶rt;am m a¶rt;umaa (185 u 272 ). ama au a amu u u u. ¶rt;nu¶rt; (10.5–12 ¶rt;) um aum anum¶rt; u m.

     

Single- and inter-station transfer functions for non-synchronous geomagnetic arrays — I. Theory of methods used in data analysis

Summary The theory of the multivariate coherence analysis(spectral domain approach) is developed for calculating single- and inter-station transfer functions and corresponding vector induction characteristics from time variations of the geomagnetic field components. An alternative approach of calculating similar induction characteristics using a time domain algorithm is shown.

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aam mu m aaua(nma n¶rt;¶rt;) nuuu ama ¶rt;-u -mau n¶rt;am u u mmmu m aamumu u¶rt;uu n anua auau mau aum n u. u¶rt;um ma m¶rt; u aau aamumu u¶rt;uu nm ama amu un mua um. nuam aum na auu am u aamum ¶rt; n ama naam.

     

Equations of motion of the moon retaining higher harmonics in the force function

u u u u uu smu um ¶rt;um ¶rt; a, s¶rt;a ¶rt;a ¶rt;u suu (n — mn, k — n¶rt;): saumauo n u: n=2, k=0; n=2, k=2; n=3, k=0, 1, 2, 3; n=4, k=0; n=4, k=3; saumau n : n=2, k=0; n=2, k=2; saumau n a: n=2, k=0.

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Dedicated to Prof. RNDr. Emil Buchar, DrSc., Corresponding Member of the Czechoslovak Academy of Sciences, on the Occasion of His 75^th Birthday     

Reaction of linear gravimetric measuring systems to disturbances of equilibrium state

Summary The reaction is studied of measuring systems of quartz gravity meters to external disturbances. The actual elastic system is approximated by a model of a linear oscillator with one degree of freedom. The appropriate differential equation of motion is solved for some of the typical shapes of determinate and random disturbance input signals. The result represents expressions which describe the time behaviour of the output signals.

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¶rt;m au uum um aaum m u u. mua na uma annuum ¶rt; u uma ¶rt; mn ¶rt;. mmm au ¶rt;uu a ¶rt; m munuu u¶rt; n¶rt; a au ua a ¶rt;. mam m au, nuau n¶rt;u ua a ¶rt; auumu m u.

     

The connection between characteristic values of the 11-year cycles of solar and of geomagnetic activity

Summary Using the annual values of the indices of solar and geomagnetic activity for the period 1868–1976, the basic values characterizing the cycle as a whole were determined for the 11-year cycles nos 11–20, (Tab. 1). High values of the coefficients of correlation were found for some pairs of characteristic values of the same and different kinds, given in Tab. 2, which can be utilized for long-term predictions of geomagnetic activity.

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a auu¶rt;u au u¶rt; uaum amumu muu 1868–1976 n¶rt; ¶rt; 11-mu u 11–20 naam aamuu u a (a. 1). u au uuma uu ¶rt; m na naam ¶rt;ua u ¶rt;ua ¶rt;a (a. 2), m m amu nuu nu ¶rt; nuauuaum amumu.

     

The earth-moon-sun disturbing function in satellite orbit dynamics

am ¶rt; a uu u m nu uu n ¶rt;uu um nmua u aumau n m -a-. ¶rt;a ¶rt; 4- n¶rt;a um.     

Intensity of vlf and elf phenomena in the outer ionosphere

Summary Spatial and temporal variability of natural ELF-VLF phenomena field intensity has been studied using data from Interkosmos satellites with apogees below 2000 km. The results show a distinct dependence of the diurnal variation and latitudinal intensity distribution on the magnetic activity. The L-value at which the maximum of plasmaspheric noise occurs, e.g., correlates better with the Dst-index than with other indicies.

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mama u a auau anmu n mm - u a ua a uu ¶rt;a uu m an u 2000 . mam naam m auum m ¶rt;a u um an¶rt;u uu m aum amumu. uua L-naama, a m nm au naa uu, um Dst-u¶rt; ¶rt;uu u¶rt;auaum amumu.

     

УСТАНОВКА ПРИЛИВНОй НАКЛОНОМЕРНОй АППАРАТУРЫ С ЦЕЛЩЮ ПОЛУЧЕНИЯ НАИБОЛЕЕ ДОСТОВЕРНЫХ РЕЗУЛЬТАТОВ

Zusammenfassung Es wurden verschiedene Installierungsmodifikationen von Neigungsmessern auf tschechoslowakischen Gezeitenstationen experimentall untersucht. Es zeigte sich, dass weder eine hohe innere Genauigkeit, noch die Übereinstimmung von Messergebnissen als genügende Bedingung für die regionale Representativität angesehen werden kann (Tab. 1, 2). Zur geophysikalischen Deutung der Ergebnisse ist daher eine einheitliche Installierung der Neigungsmesser und eine Überprüfung der Repräsentativität der Ergebnisse unbedingt nötig.

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3. 3 , 1975)