Bucharest, the capital of Romania, with more than 2 million inhabitants, is considered after Istanbul the second-most earthquake-endangered metropolis in Europe. It is identified as a natural disaster hotspot by a recent global study of the World Bank and the Columbia University (Dilley et al., 2005). Four major earthquakes with moment-magnitudes between 6.9 and 7.7 hit Bucharest in the last 65 years. The most recent destructive earthquake of 4. March 1977, with a moment magnitude of 7.4, caused about 1.500 casualties in the capital alone. All disastrous earthquakes are generated within a small epicentral area – the Vrancea region - about 150 km north of Bucharest (Fig. 1). Thick unconsolidated sedimentary layers in the area of Bucharest amplify the arriving seismic shear-waves causing severe destruction. Thus, disaster prevention and mitigation of earthquake effects is an issue of highest priority for Bucharest and its population.

          As a major scientific aim we will develop calibrated seismic response laws which can be used to describe the seismic wave amplification in Bucharest. Several seismic observation stations from different institutions are running in the Bucharest area to record seismic waves. There are also numerous shallow boreholes from different institutions which were used to map the subsurface lithology. However, there are only 12 boreholes which were partly geotechnically investigated to relate the local geology with seismic wave propagation properties.

Therefore, the main purpose of this project is to obtain a unique, homogeneous dataset of soil-mechanic and elasto-dynamic parameters of the subsurface of Bucharest from 8 new boreholes to model the so-called seismic site responses.

In a second step these modelled site responses will be compared to already available observed site responses (measured seismograms) to find the relationship between the measured subsurface rock properties and the observed seismic amplitudes.

Then this calibrated relationship can be applied to other available borehole lithologies in the metropolitan area of Bucharest. Thus in the end this research programme will help to develop an optimised seismic microzonation of the metropolitan area of Bucharest which will be implemented for the future urban planning.