Boundary of recent activation and seismicity on the platform part of Ukraine

Abstract

The purpose of the work is to clarify the boundaries of the recent activation (RA) zone in the platform part of Ukraine. Such limitations are evident for the Alpine Carpathian geosyncline and the Hercynian-Cimmerian Scythian plate. For the East European Platform, the edge of the zone is determined by the magnitude of the mantle gravity anomaly. This option gives a more definite result than the previously used complex of geological and geophysical data. The applied technique, in addition to the usual two-dimensional density modeling along DSS profiles, includes the processing of the obtained data by kri­ging. This allows you to fill in the area between the profiles and trace the detailed shape of the zone boundary. The magnitude of the anomaly at the edge of the active region was calculated. In the center of the zone, the studied perturbation (the difference between the gravitational effect of the crust and the observed field) is 30—40 mGl, at the edge — 20 mGl. An estimate of the error in determining the anomaly was made, it turned out to be at the level of 10 mGl. The value at the boundary is less than the tripled error. In this situation, a special procedure is needed to detect spatial variations in the position of the boundary. For this, for the first time, two of its calculation options were used: using kri­ging and using artificial profiles located between the real ones. The crustal sections under the artificial ones were average between the real ones, the observed field on the artificial profile was used. An average difference in the boundary position of 13 km was obtained. The practically important question of the ecological consequences of manifestations of activity in the RA zone on the platform is considered. Seismicity does not pose a significant threat, as does the release of helium with anomalous isotopy and hydrogen. Catastrophes happen precisely during the exploitation of gas and coal deposits, and not as a result of the natural evolution of these objects.