earthquakes землетруси землетрясения Dnieper-Donets depression a seismic centre a tectonic structure of the Dneprovsko-Donetsk depression acoustic methods characteristics of sattelites cloud anomalies deep canyons deep faults degassing displays of clouds anomalies on the satellite images displays of the methane macroleakages on satellite images forecasts fractured zones gas flares gas vultures gashydrates geological structure linear cloud anomalies methane gas emissions model of the avalanche-unstable formation of cracks mud volcanoes satellite imagery satellite monitoring seasonal thermocline seismic activity spectral characteristics statistical relation between deep faults with oil and gas presence