Goal: - to analyze the focal parameters of Crimean earthquakes determined from records of analog and digital seismic stations; - to draw a conclusion about the degree of their correspondence and continuity to the properties and regularities received earlier with the use of only analogue equipment. Methodology. We have chosen the earthquakes in the south of Ukraine registered parallelly by two kinds of seismographs at the “Simferopol” and “Alushta” stations. The calculation of the amplitude spectra by analogue seismograms was done by the rapid method of characteristic points, whereas the calculation of the amplitude spectrums by digital seismograms was done by Fast Fourier Transform. Approximation of the spectra and the source dynamic parameters assessment was performed within the framework of the Brune theoretical dislocation model. In this model the amplitude spectrum of volume waves is described by three parameters: spectral density Ω 0 in the long-period part (at f →0), angular frequency f0 and inclination angle ~ –2. Source dynamic parameters have been computed by the characteristics of the amplitude spectrum, spectral density Ω 0 and angular frequency f0: seismic moment M0 and radius of the circular dislocation r 0. Results. It has been shown that seismic moments M0 and moment magnitudes Mw by the analog and digital records correspond to each other and the radii of the circular dislocation r0 according to the digital stations are somewhat larger compared to the analog ones at the expense of a more broadband amplitude- frequency response of digital devices. Independent estimates of M0 and r0 and digital seismic records for the period 2001-2011 have been used to calculate the correlations of these parameters on the energy level of earthquakes (Кп). Within the error of their construction the new М0(Кп) and r0(Кп) are close to the long-term for analog recording. Scientific novelty. For the first time, we have obtained a quantitative study of correspondence of spectral and focal parameters reconstructed from the records of analog and digital seismographs, as well as of the continuity of their previously established long-term properties and laws. Practical significance. New data on the digital stations significantly complement the statistics on the focal parameters for use in the study of geodynamics and modeling of seismic effects (accelerograms) at construction sites.
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