ДИНАМИЧЕСКИЕ ПАРАМЕТРЫ СИЛЬНЫШ ЗЕМЛЕТРЯСЕНИЙ ПО ДАННЫМ ШИРОКОПОЛОСНОЙ ДЛИННОПЕРИОДНОЙ АППАРАТУРЫ

Summary The dynamic focal parameters of a series of strong earthquakes, recorded by the FBV broadband velocigraph at KHC (Kaperské Hory, Czechoslovakia), are estimated. The influence of specific wave pattern features on the estimation accuracy is studied. Polarization analysis is used to demonstrate the complicated interference character even of record portions corresponding to a single teleseismic wave group. The values of the dynamic focal parameters do not depend significantly on the length of the analysed record portions and are sufficiently consistent with those reported by Riznichenko [2]. The possibility of estimating dynamic focal parameters from recording of standard classes B (intermediate band) and C (long-period) seismographs is pointed out.     

Tensional crack development in physical models with inhomogeneities under load

Summary The paper deals with a study of the mean stress field (_M) and its gradient (_M/x) in uniaxially loaded two-dimensional models of small thickness with respect to other dimensions, in which two inhomogeneities, e.g., a circular opening and a linear slit have been made. Particular attention was paid to the stress field development in the treated models durin gthe change of the mutual geometric configuration of both the inhomogeneities in question. The problem was analysed theoretically by means of Muskhelishvili's potentials of the two-dimensional theory of elasticity. To compare the results of calculations, the schlieren method was used to visualize and record the studied gradients of stress fields in physical models. The results of the calculations were calibrated by laboratory tests. In this way the individual model situations were classified from the point of view of their resistance to the applied load.     

Numerical modelling of geoelectric structures using the galerkin and finite elements methods

Summary The Galerkin and finite elements methods are used to model numerically H- and E-polarized electromagnetic fields in inhomogeneous media. The error of approximation is studied and an example of numerical results is given.     

Heat flow and gravity in Czechoslovakia

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