DETERMINISTIC EARTHQUAKE SCENARIO FOR THE CITY OF VARNA

Abstract

In the present study deterministic earthquake scenarios for the city of Varna - the thirdlargest city in Bulgaria are presented. By deterministic scenario, it is mean a representation of the severity of ground shaking over an urban area, using one or more hazard descriptors. The assessment of seismic hazard and generation of earthquake scenarios is the first step of seismic risk evaluation and society prevention. Seismic history of Varna shows that the hazard for the city is mainly influence by the earthquakes occurred in the seismogenic zone Shabla (Kaliakra fault system). The local ground shaking levels are computed using the six ground motion prediction equations (GMPE�s) for tectonically active regions that are previously selected. A reliable geotechnical zonation of the city of Varna was incorporated in the earthquake scenario generation. Deterministic ground shaking scenarios for the city of Varna are generated for two scenario earthquakes with different location and magnitudes are considered. The generated scenarios are described in terms of MSK (=EMS98) intensity, peak ground acceleration and velocity and in spectral accelerations for Sa (0.3s) and Sa (1.0s). The results in PGA and MSK intensity for scenario MW7.2 quake located on strike slip Kaliakra fault are mapped. The estimated peak ground accelerations for MW7.2 quake vary between 0.07 and 0.14 g.