Seismic hazard mapping of Ohrid, North Macedonia

Abstract

AbstractThe city of Ohrid is one of the oldest settlements in the western Balkans, exceptionally rich with archeological, architectural, and cultural sites, which must be protected from damage during future earthquakes by proper retrofitting and strengthening of the old structures. To provide a sound basis for retrofitting work, in this paper, we describe the amplitudes of strong ground motion in Ohrid for a range of probabilities of being exceeded. We use the Uniform Hazard Method to compute the amplitudes of strong motion, and, in the calculations, we explicitly include the geological site conditions for all the maps we show. By noting the large jumps in the predicted strong motion amplitudes at sites along the contact between basement rock and sediments, we emphasize that the empirical scaling equations for strong motion amplitudes must include explicit dependence on the geological site conditions.