Gravity potential of the normal body in the outer and inner space

Summary The level rotational ellipsoid, best fitting the actual Earth, rotating with the same angular velocity around a common axis of rotation, is assumed to be a mathematical model of the real Earth. The gravity potential of this body and its derivatives in the outer space are derived by means of the generalized Pizzetti method[1]. For some analyses of the structure of the Earth we need to know the gravity anomaly and thus the gravity potential and its derivatives inside the mathematical model. These values are not defined in the classical conception. In this paper, the normal potential and its derivatives in the inner space are derived up to a certain depth, which is still of significance for gravimetric research.Dedicated to RNDr Jan Pícha, CSc., on his 60th Birthday     

On the solution of the boundary problem of the potential theory by means of the vertical derivative of the gravity anomaly

Summary The boundary problem of the potential theory is treated for the case in which the values of the vertical derivative of the gravity anomaly are known. There boundary conditions are derived and alternatives are also treated.Dedicated to RNDr. Jan Pícha, CSc., on his 60th Birthday     

Investigation of the damping of geomagneticPi2 pulsations using generalized spectral analysis

Summary The method of spectral analysis has been modified to render the spectrum not only a function of frequency, but also of damping. The generalized spectra of damped geomagnetic pulsations, recorded at the observatories of Budkov and Dymer, are computed. The degree of damping of these pulsations in the X and Y-components at both stations is determined. The results are compared with results obtained using other methods.     

Effect of the anomalous part of the atmosphere on the observed acceleration of gravity

Summary With the aid of a simplified model, the gravitational effect of the anomalous part of the atmosphere was analysed theoretically and formulae were derived for numerical computation. It was found that under extreme meteorological conditions this effect is of the same order as the present accuracy of absolute gravity observations, i.e. ±100–150 nm s^–2. It is, therefore, recommended to reduce these observations to some model of the normal atmosphere by introducing computational corrections.     

Transmitted waves in the vicinity of the interface beyond the critical point

Summary The space (time) delay of transmitted waves in the vicinity of the interface beyond the critical point is investigated on two-dimensional seismic models of a low velocity channel; results of laboratory experiments are compared with the conclusions of the theory. The effect of the time delay in field measurements is demonstrated by means of two typical geological formations.     

Macroseismic effects of the north-Italian earthquake of May 6th, 1976, on the territory of Czechoslovakia

Summary The method of treatment of the macroseismic data obtained on the territory of the CSSR after the main 1976 Friuli earthquake is described and the preliminary results are confronted with the geologic structure.     

Heat production data from airborne and laboratory measurements of gamma-ray activity of rocks

Summary The paper discusses the obvious experimental relation between the laboratory determinations of total gamma-ray activity, expressed in equilibrium uranium concentration, and heat production due to radioactive decay. The heat production data were calculated by means of the concentrations of uranium, thorium and potassium determined spectrometrically, together with the conversion factors into the rate of heat generation. The obtained relation may help define the typical heat production for characteristic surface rocks and estimate their contribution in heat flow study. Between the gamma-ray activity recorded during aeroradiometric mapping and the laboratory radiometric measurements of surface rock samples, there is also an experimental relation, which can be used further in estimating the value of surface heat production at a chosen locality.     

The interplanetary magnetic field sector structure and meteorological microseisms

Summary Meteorological microseisms, recorded at the Prague seismic station and, similarly, at other Central Europe stations, reflect certain meteorological situations in the North Atlantic frontal zone. Meteorological elements in this zone are affected by some factors of extra-terrestrial origin, among others by the interplanetary magnetic field (IMF) sector structure. The analysis of the 68 IMF sector boundary passage effects in microseismic activity, expressed in microseismic amplitudes, showed a well-developed minimum of microseismic activity on the day of the boundary passage in winter, but no such effect in spring and autumn. In spring and autumn, however, a tendency was observed to slightly higher microseismic activity in the away (+) sector, whereas no such tendency was observed in winter. These results agree with the IMF effect found in the troposphere. Generally, the IMF sector structure is only a modulating rather than a major factor controlling the microseismic activity.