An effective method of frequency analyses of time series of geo-physical quantities

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Results of the earth-tide measurements at the Pecný station (CSSR)

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Paper presented at the IUGG XVII Plenary Meeting, Canberra, Dec. 1979.     

Approximate expression for the hilbert transform of a certain class of functions and their application to the ray theory of seismic waves

Summary Approximate expressions for the Hilbert transform of the functionf(t)=exp(- ₀ ² t ²/²) cos( ₀ t+v) are determined. This function, given a suitable choice of the three parameters ₀, and v, approximates a wide class of seismic signals very well. The approximate expressions for the Hilbert transform enable very simple formulae to be given for the elementary seismograms of the individual seismic body waves (in the zero approximation of the ray theory). This accelerates the computation of ray theoretical seismograms considerably.     

Obliquity of potassium feldspars in the differentiation series of minettes

Summary The individual rock types of the differentiation series of minettes display different obliquity of potassium feldspars. In minettes,sensu stricto potassium feldspars with disordered monoclinic structure occur, in alkaline minettes both microcline and orthoclase are present, and in alkaline microgranites and microsyenites only microcline occurs. It may be assumed that the main factors controlling the ordering of K-feldspar structures in alkaline members of the minette series were the decrease of temperature below that of the orthoclase-microcline inversion and the presence of alkaline hydrothermal solution in the crystallizing magma.

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Die Triklinität der Kalifeldspäte in der Differentiationsreihe der Minetten

Zusammenfassung Die einzelnen Gesteinstypen der Minetten-Differentiationsreihe enthalten Kalifeldspäte mit unterschiedlich geordneten Strukturen. Minettensensu stricto enthalten Kalifeldspäte mit ungeordneter monokliner Struktur; Alkaliminetten sowohl Mikroklin als auch Orthoklas; Alkalimikrogranite und-syenite hingegen nur Mikroklin. Die Ordnung der Strukturen der Kalifeldspäte in den Alkaligesteinen wurde wahrscheinlich durch den Temperaturfall unter die Temperatur der Orthoklas-Mikroklin-Inversion und durch die Anwesenheit alkalischer hydrothermaler Restlösungen im kristallisierenden Magma bewirkt.

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With 1 Figure     

“Spectral ω2 model” and variable absorption coefficient

Summary Aki's spectral ² model[1] is used to estimate the amplitude field at epicentral distances up to 1000 km in the case of an absorption coefficient of seismic waves which varies with distance. Velocity spectra, the periods of the maximum of these spectra and the maximum velocity amplitudes are obtained. The results are compared with[2] and it is shown that the divergence of the amplitude field decreases if a variable absorption coefficient is used. The theoretical results, obtained in this case, approach the results seen in practice. The possibility of determining the limits of epicentral distances, at which the amplitude field may be considered as linear, is given.     

Regional trends in European induction data

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Dynamic loading of the boundaries in the finite-difference study of diffraction

Summary The finite-difference method can be used for obtaining the theoretical seismic response of a block structure to an incident plane wave. Computer time is saved by solving an equivalent problem of dynamic loading of the boundary of the block structure. The loading is performed by means of a set of discrete body forces, replacing the incident wave at the interface.