Expert Assessment of the Displacements Provoked by Seismic Events: Case Study for the Sofia Metropolitan Area

The paper discusses the very recent seismotectonic and geological investigations for the Sofia valley. It also reviews available historical and recent seismological data. One possible variant of seismic zoning (interpretation of available geological and seismological data) is used to evaluate uniform probability Fourier spectra of strong ground motion at Sofia City. The distribution of the maximum expected displacements, using 1-D models and SHAKE’91 techniques for 50 years of exposure time is mapped. The maps of eigensolution results for 30 m, 50 m depths to the rock are illustrated. These issues are important for definition of design parameters for evaluation of seismic safety of underground infrastructure, as well as for tall structures.