Characterization of Seismogenic Zones of Romania

Abstract—Although the time and magnitude range covered by available seismological data is limited, several significant regional trends are outlined in the seismogenic zones of Romania. Vrancea region, which is by far the most seismically active area, has a persistent rate of occurrence of intermediate-depth earthquakes, clustered in a very confined focal volume, and a clear compressive stress regime. The deformation field, as deduced from the available fault plane solutions, is drastically reduced in the crust, where the maximum magnitude is below 6.5 (except Shabla zone, in Bulgaria). The system of major faults developed in a NW–SE direction in the Carpathians foredeep area is certainly linked to the subduction process in Vrancea, although they seem not to play a significantly active role, as could be expected for an active subduction process. The existing data indicate an extensional deformation regime over the foredeep area and Southern Carpathians, while a predominant compressive regime is outlined at the contact between the eastern margin of the Pannonian Depression and Carpathians orogen, in agreement with the bending tendency of the maximum horizontal compression orientation of the crustal stress field from NE–SW, in western and central Europe, to E–W, in the intra-Carpathian region (Grünthal and Strohmeyer, 1992).