Seismic shaking scenarios for city of Dubrovnik, Croatia

The south-eastern part of Adriatic Sea is seismically highly active region where numerous strong events have occurred in historic times. Among these, the most significant is the infamous Great Dubrovnik earthquake of 1667. This event, whose magnitude was estimated to be in the vicinity of Mw 7.0, caused widespread devastation in the whole region. More recently, a large Mw 7.1 event happening in 1979 in Montenegro caused extensive damage along 100 km of coastline, including the area around Dubrovnik. From this it is obvious that the city of Dubrovnik is seismically highly vulnerable and that there is an acute need to better understand possible consequences if an event of such a magnitude would happen today.  
 
One of the major steps in reducing the seismic risk in any region is to simulate seismic shaking and to evaluate expected ground motion for plausible earthquake scenarios. Therefore, our aim in this work is to create several earthquake scenarios for the city of Dubrovnik and estimate seismically most endangered parts of the region. For that purpose, we first assemble a detailed 3D crustal model which includes information on physical parameters of interest (velocity and density) and which reflects all the important geological features of the studied area. Then, we test whether the model is suitable for simulation by computing and comparing broadband seismograms against the recorded data of several moderate events. We validate the results by assessing the goodness of fit for different metrics describing ground-motion. Next, by combining seismic and geophysical data, we define the geometry of the main active faults and parameters required for the rupture model used in the simulation. We calculate synthetic waveforms on a dense grid and then extract intensity measures to determine the expected ground-motion features of a strong seismic event such was The Great Dubrovnik earthquake.