The seismic hazard assessment in dense-populated areas and the strategic objectives design are based on the study of seismicity of the seismogenic sources (which can have an effect at the site above a specified minimum level that is considered risky) and the attenuation between focus and site. The purpose of this paper is to provide a complete set of information required for a probabilistic assessment of the seismic hazard in the southeast Romania relative to the following seismic sources: Vrancea zone (in the crust and intermediate-depth domains), Predobrogean depression zone, Intramoesian zone and Shabla-Dulovo (Bulgaria) zone. As an example, the obtained input parameters are used to evaluate the seismic hazard distribution due to the crustal earthquakes applying the McGuire's procedure (1976). These preliminary results are in good agreement with the previous research based on deterministic approach (Radulian et al. 2000).
Attenuation specific from Vrancea intermediate-depth focus toward SE is revised at length in order to re-evaluate the seismic hazard at the nuclear power plant (NPP) Cernavoda. To this aim, we took into consideration all the strong motion data available for the region and test a large range of relationship types. Since the instrumental data are limited as magnitude and depth intervals, the extrapolation based on the attenuation laws deduced from these data to great magnitudes is very instable and must be carefully considered. The extrapolation outside the characteristic domain of the available database leads to large deviations, especially at large magnitudes and for the relations which contain the depth as independent parameter.