Vrancea Seismic Zone, East Carpathians, Romania: Past Regional Geodynamics and Actual Active Tectonics, Causes of Deeply Located High Magnitude Earthquakes

A recent comprehensive study, considered as important for the geodynamic, crustal and lithospheric geological structures and active tectonics in Vrancea, presented geological updates based on geophysical and geological data interpretation: a) Wrench tectonics system, crossing NE-SW the Romanian territory; b) Romanian Trough, interpreted as the prolongation of the Polish Trough beneath the East Carpathians; c) Volcanism and intrusive processes in the Vrancea area; d) Geophysical and tectonic model for the Vrancea seismic zone. When interpreting causes of Vrancea zone crustal seismicity, they are here considered to be associated at crustal depths with active normal faults situated within a graben geological structure, in an extensional regime. At lithospheric level the causes of high magnitude seismicity are related to strike-slip movements of a regional transcurrent fault, in a transtensional regime. High magnitude seismic events are considered to be located at the junction of the WT Southern Fault with a NW-SE trending strike-slip regional fault system, namely the Peceneaga-Camena, Capidava-Ovidiu and Mangalia faults.