The physical properties of tidal gravimetric instruments allow recording, not only tidal effects, but also waves generated by earthquakes. Three gravimetric stations with determined transfer functions and co-located seismic stations from the observatories in Western and Central Europe were selected for analysis. The observatories are equipped with almost all types of sensors available on the market, which allow for thorough analysis of earthquake recordings in the period range of 10–1000 s. In total, over 10,000 traces of worldwide earthquakes were investigated. The saturation levels of gravimeters as well as a correlation between the gravimetric and seismometric signals of an earthquake were carefully analysed. A simple processing scheme of gravimetric signal of earthquakes was adopted thanks to the probabilistic power spectral density analysis of continuous recordings. The detail analysis of transfer function of gravimeters allowed to define a period range when a sensitivity coefficient (calibration factor) and a time lag value only can be used to properly describe the properties of instruments. What’s more, it has been shown based on the calculated group-velocity dispersion curves of fundamental mode of Rayleigh waves, that the Earth’s mantle structure can be determined for greater depths from the recording of tidal gravimeters than from typical broad-band seismometers.
The aim of this paper is an investigation of damping properties of polyurethane materials that were produced from polyurethane foam granules. There were used polyurethane materials with different thickness and inertial masses. After measurements of damping vibration, the polyurethane samples were compared and recommended in reference to their damping properties. and Tématem tohoto příspěvku je vyšetření tlumících vlastností polyuretanových materiálů vyrobených z polyuretanových pěnových granulí. Byly použity polyuretanové materiály s různými tloušťkami a setrvačnými zátěžemi. Po provedení měření útlumů vibrací polyuretanových vzorků byly jednotlivé vzorky porovnány a doporučeny z hlediska jejich tlumících vlastností.
For investigation of influence of various subsoil geological structures on spectral acceleration amplitudes of foundation soil it is necessary to continue in long time monitoring of near seismic events by using of large number of field accelerometers. The new special apparatus for automatic recording of spectral acceleration response was constructed. Principle of this apparatus is reverse pendulum with piezoelectric converter. This simple construction makes possible production numerous series with small requirements on capital expenditure and installation. The function of developed apparatus prototype was field-tested in station Prague - Květnice. Various seismic signals were recorded and also response amplitude of earthquake with focus near Červený Kostelec (10 October 2005, 10 : 51 : 57.4 ; M = 3.4; R = 156 km; φ = 50.47; λ = 16.07)., Jiří Buben and Vladimír Rudajev., and Obsahuje bibliografii