Том 53, № 2 (2017)

The paper presents results of studying the attenuation of ground accelerations from earthquakes of the Vrancea with magnitudes less that 6.0 at distance greater than 300 km in a narrow sector located northeast of the focal region, within the limits of which are located acting and planned nuclear power plants (NNPs). Attenuation of peak ground accelerations in individual sections along the Vrancea–IRIS OBN station path is approximated by individual functions. It is shown that for a rough estimation of the seismic effect of earthquakes from the Vrancea zone it is acceptable to use the empirical relationship obtained by F.F. Aptikaev. For a more accurate estimate, it needs to be modified by adding a constant, whose value depends on the specific conditions of the NPP sites. It is shown that the results of data analysis on moderate earthquakes can be extrapolated to an earthquake with the maximum possible magnitude for the Vrancea zone and used to estimate the maximum seismic effects at the sites of operating and planned NPPs.

The results of a macroseismic study of the late medieval Turkish Yeni-Kale fortress in Eastern Crimea are described. Despite the fact that the fortress’ structures were considerably affected by local landslide activity, military operations during the Crimean War, the Civil War, and the WWII, as well as by anthropogenic factors, such as railroads, etc., numerous specific deformations in the fortress walls suggest that the existing destruction and damage might be explained by strong seismic impacts. The local intensity of seismic oscillations could be I = (VIII)–IX points according to the MSK-64 macroseismic scale, and the direction of the combined maximum seismic impact could have a NW–SE strike. It is likely that the Turks abandoned the fortress without a battle because of its significant seismic damage and destruction in the 18th century, which had not yet been repaired by the time the Russian army arrived.

Macroseismic data on strong historical earthquakes of the 18th–19th centuries are presented that are unknown to a wide range of seismologists and therefore missing in earthquake catalogs. The data are related to such earthquakes as the 1715 (1716) Nerchinsk and 1727 Kirensk, and ones occurred in the southern Baikal region in 1809 and in the region near cape of Svyatoi Nos in 1862. Additional information about the earthquake of 1771 is given that considerably refines the parameters of this event. The earthquakes of 1725, 1742, 1772, and 1885 and interpretations of evidence doubted by various researchers are also considered.