VRANCEA EARTHQUAKES AREA, ROMANIA

Oceanic lithosphere does not subduct (or might not do) uniformly (K.Hirosha, 1999, Nature). Consequently, due to differentiately advancing of the Alpine Plate onto East European one, combined with Moesian one, and all as a result of pushing at continental scale from African and Arabian Plates and being stopped by East European Plate, a 3D rotation should have resulted in horizontal pane, combined with a rotation in the two rectangular vertical planes, and all of these in Vrancea earthquakes area. Our model implies that a break-up of the lithosphere should have taken place in Mesozoic times, on a NE-SW direction. This involved also the break-up of the lithospheric lower mantle with all implying phenomenon. We assume that the spreading axes were N-S directed with transform faults more or less perpendicular to them, as it is now on the middle of Atlantic Ocean. The break-up of the oceanic crust is marked by ophiolites suites and geophysical data. Finally a suture zone is evidenced in Transylvanian basin, on a NE-SW direction. Paleomagnetic data (Patrascu et al., Mauritsch et al., Tectonophys., 1994-1998) suggests that Apuseni Mountains were located at lower latitudes, and suffered a clock-wise rotation. The movement is related to the initiation of rifting, in the Late Jurassic- Early Cretaceous times. Dobrogea area is in our model drifted away from its original location, all along the the South Transylvanian strike-slip transcrustal fault. This is somehow sustained by the fact that ophiolites suites in Dobrogea area present some similarities with Mures zone suites, and we have assumed that both have a more or less origin. Forms of life of Proterozoic ages, found in green schist rocks in Dobrogea (Histria nappe) suggest that it was a border plate during the Proterozoic times. Furthermore, stress data analysis suggests that it suffered an anti-clockwise rotation, and that fits well with our model. Earthquakes occurrence in Vrancea area (Romania) is a cyclic phenomenon. Wavelet transform was applied to analyze earthquakes occurrence in Vrancea area, FFT methods and neural network techniques. We found a periodicity of 2 x 11 years for earthquakes with magnitude greater than 6 degree on Richter scale, with reversed polarities. This is in good agreement with the cyclic behavior of the Sun magnetic field. (Nature, 408, 2000).