Stress field in the earth's crust with curved boundaries

Summary A two-dimensional theory of gravitational stresses in the Earth's crust with curved boundaries is presented. The crust is modelled by an elastic plate lying on an elastic half-space. The solution obtained in the case of periodically varying boundaries is shown to be very sensitive to the ratio of both elastic parameters. Moreover, the geometrical configuration of both boundaries and their phase shift are of great importance for the resulting stress pattern.     

Precipitation of electrons after geomagnetic substorms

Summary Precipitating electrons E_e>10 keV and E_e>30 keV and protons E_p=150 to 300 keV are analyzed using data obtained from the low-altitude polar-orbiting satellite Interkozmos-17 after the magnetic storm of December 2, 1977. On December 3, an isolated substrom occurred, and strong electron precipitation was observed in the midnigt sector, while the sequence of substorms of December 5 expanded its longitudinal extent from 22 MLT through the morning to 12 MLT. The different character of the precipitation, in the two cases mentioned, is discussed in relation to the changes of conditions for the generation of cyclotron instability as well as to the effect of particle injection. Proton precipitation occurred only in the night sector, most probably just inside the plasmapause.

---

¶rt; aau nau m E_e>10 u E_e>30 u nm E_p=150–300 n uu n uuma nmua n um m-17 n aum u 2. ¶rt;a 1977. 3. 12. nua uuaa u u nau m aumua m mo u. a n¶rt;amm 5. 12. nua auu ¶rt;m umaa, m m nau, a u m 22 MLT mu m ¶rt; 12 MLT. a aam nau nu¶rt; ¶rt; a ¶rt;am aa uu u ¶rt; uu um mumu u ¶rt;mu uuu amu. nau nm n¶rt;u m m u m a naana mu naa.

     

Three-dimensional inverse problem for inhomogeneous transversely isotropic media

Summary The basic formula used in the presented paper gives the relation between the P wave travel-time perturbation and the perturbation of an inhomogeneous transversely isotropic medium, expressed by four perturbations of elastic parameters and by two angles of orientation of the axis of symmetry of transverse isotropy in space. The travel time perturbation is computed along the ray in the unperturbed inhomogeneous isotropic medium. Four elastic parameters and two angles are parametrized in the model under study and a system of equations for many rays is constructed. The equations are linear in the sought elastic parameters and nonlinear in the sought angles, and the iterative Levenberg-Marquardt algorithm is thus used to solve them. The theoretical 3-D inverse problem was solved in the presented numerical example. The data, simulating teleseismic data, were computed in the direct problem and then inverted. The results indicate the applicability and limitation of the presented algorithm in real problems.

---

a a, unaa n¶rt;aa am, ¶rt;am mu ¶rt; uu u na u uu ¶rt;¶rt; nn umn ¶rt;, a m nuu naamau u ¶rt; au umauu u umuu nn umnuu nmam. u u na um ¶rt; a aa ¶rt;¶rt; umn ¶rt;. nu naam u ¶rt;a a naamuua ¶rt;u u nma uma au ¶rt; u . au u n um nu naama u u n um a umauu umuu, nm un m umamu aum a-aa¶rt;ma ¶rt; u u. am nu¶rt; ¶rt; m u nu. nu muu ¶rt;a aaa a na a¶rt;aa u am ¶rt;a a. mam naam auu u mu nuu nu¶rt;uma a a.

     

The periodicity of aurorae in the years 1001–1900

Summary The sequence of aurorae, observed at latitudes up to 55° between the years 1001 and 1900 was processed by methods of spectral analysis. The same methods were applied to parts of various duration of this interval. The periods predominant in the time series under investigation were determined. In all the selected parts of the interval, these periods are always located within the same frequency band. Their position is related to the periods corresponding to mutual conjunctions of the large planets.

---

¶rt; n uu, a¶rt;au a uma ¶rt; 55° nu¶rt; 1001–1900, ama nu nu m¶rt; nma aaua. a n¶rt; ¶rt; am a ¶rt;u m umaa. u n¶rt; na¶rt;au nu¶rt; u¶rt;a ¶rt;a. mu nu¶rt; ¶rt; a am umaa ¶rt;a a¶rt;m ¶rt;ua ¶rt;uaan amm. nu mum nu¶rt;au, mmmuu au u u nam.

     

Comparison of electric and elastic parameters of indian precambrian rocks

Summary Examination of the relation between electric resistivity, compressional wave velocity and density of Indian Precambrian rocks is presented.

---

¶rt;m auumu ¶rt; muu nmuu, m n¶rt; uu u nmm ¶rt;uu n¶rt; u ¶rt;uu.

     

Long term variation in the secular love number

Summary It has been demonstrated that the observed decrease in the second zonal geopotential harmonic linear in time and the secular decrease in the angular velocity of the Earth's rotation do not satisfy the relation defining the secular Love number k as constant during the whole history of the Earth's evolution. The discrepancy disappears if it is assumed thatdk/dt=–2.4×10^–6 cy^–1 .

---

aa, m a ¶rt;a au m aauunmuaa u u a ¶rt;a u mu au u ¶rt;mm mu, n¶rt; u a a nm mu umuu u. a uam, u ¶rt;nmumdk/dt=–2,4·10 ^–6 (mmu)^–1 .

     

On the detection of weak strain parallel to the bedding by magnetic anisotropy: A mathematical model study

Summary Five mathematical models of the superposition of deformational magnetic fabric on sedimentary magnetic fabric are presented. These models are represented by various combinations of pure shear and simple shear. The diagrams of the variations in the main magnetic anisotropy parameters with strain can help in recognizing weak ductile deformation in sedimentary rocks.

---

Реэюме Пруво?rt;umся nяmь мamемamuческuх мо?rt;елеŭ суnерnозuцuu ?rt;еформaцuонноŭ мa?rt;нumноŭ mексmуры на осa?rt;очноŭ мa?rt;нumноŭ mексmуре. Мо?rt;елu ире?rt;сmвaлены в рaзных комбuнaцuях чuсmо?rt;о с?rt;вu?rt;а ц иросmо?rt;о с?rt;вu?rt;а. Дua?rt;раaммы вaрuaцuŭ в ?rt;лaвных naрaмеmрaх мa?rt;нumноŭ aнuзоmроnuu с ?rt;еформaцuеŭ мо?rt;уm nомочь nрu рaсnознaвaнuu слaбых nлaсmuчных ?rt;еформaцŭŭ в осa?rt;очных nоро?rt;aх.

     

A contribution to the parameterization of total radiation

Summary To be able to parameterize vertical heat and water vapour fluxes in the boundary layer of the atmosphere, it is necessary to determined, among other factors, the amount of incident total radiation under a generally arbitrary condition of the atmosphere at any instant of time. This paper deals with a simple model for computing the total radiation based on known solar elevation, total cloud cover and the atmospheric turbidity parameter. This variant of the model was formulated on the basis of a two-year series of total radiation observations made in the radiation network of the Czech Hydrometeorological Institute, and on the measurements and observations made at the observatory of the Institute of the Physics of the Atmosphere in Kopisty. An example of comparing the observed and theoretical values of total radiation will also be given.

---

¶rt;um naamuauu mua nm mna u amu nzau am mm ¶rt; nu n¶rt;u au a nm numa a a¶rt;uauu m u. mam auam n naamuauu a a¶rt;uauu n ¶rt;a m a, ammu am u mnu az na. ¶rt;azaa ¶rt; nma a mam ¶rt;mu uu auau mu z zu¶rt;mzu z umumma u a amuu mumma uuu am numa. mam ma nu¶rt; nu au u u n n¶rt; ¶rt;u u au a a¶rt;uauu.

     

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.

---

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.

     

Global geoidal undulations as inferred from the Bruns formula and from inversion of the geopotential series

Summary The problem of inverting the geopotential series with respect to the geoid radius has been solved. A linearization of the radius powers, making use of a reference surface, has been applied. The body given by the Bruns' formula has been chosen as the reference surface. Corrections to the Bruns' formula in an analytical explicit form have been derived. An internal linearization accuracy of the order of 1 mm has been achieved. The geoid radius coefficients for the GEM-L2 model have been evaluated numerically. The corrections have been found to range from –90 to 90 cm.

---

m¶rt; uauauu ¶rt; aaumuu u ¶rt; ama a¶rt;ua — ma, m una uum au aumau n u u naam unu¶rt;a. u u¶rt; una um uum u nmuaa u uum au a¶rt;ua — ma. ¶rt;a¶rt;amua ua, aa uauau, n¶rt;a 1 . u¶rt; u am ¶rt; ¶rt;uaumau n GEM-L2. au na nm mm m am nu annuauuu¶rt;a, a a m a, n¶rt;a ± 90 .