## 2 Data and Methods Used
### Geotechnical and Geophysical Data in the Durres Region  
The mainshock struck a modern urban environment, the metropolitan area of Durres, and caused extended damage downtown as well as in several villages in the epicentral area. The recent layers of surface geology (Figures 1, 4 and 5) are related to the highest expected seismic intensities and/or PGA values [34; 53; 54; 55], as well as with problems concerning soil instabilities, such as induced liquefaction on poor sandy deposits of the Durres lagoon and the Durres Bay area [30]. The Quaternary deposits in the Durres basin include alluvial, lagoon, marshy and marine deposits with a total thickness of around 130 m [30]. The marshy Holocene deposits, comprised of clay, clayey loam, sand, and organic material, have played an important role in forming strong ground motion and distribution of the earthquake-induced building damage in Durres [56]. A large part of the city is founded on these marshy deposits, which reach a maximum thickness at the central part of the swamp. The geological properties and related lithologies of this area are also revealed by its name, \"marshes.\" The latter represents an area where expected seismic hazard can be drastically increased due to local site conditions, shallow underground water level, active faults surrounding the city and underground topography of basement rocks [30; 57]. From the expected strong ground motion, the area is classified as the most hazardous among the Albanian coastal zone based on the seismic microzoning studies (Figure 5), through spectral characteristics, seismic intensities, and expected dynamic soil instabilities [30]. Based on past seismic microzonation, the expected MSK macroseismic intensity varies between VII to IX throughout the city, exhibiting an intensity increment of more than 2 units (Figure 5a). In addition, an equal depth contour map for the city of Durres (Figure 5b), shows a 3D bedrock morphology, implying a 3D basin model. The basin is built on recent Holocene marshy deposits, clays, sands, and peat, with a part of it on Pliocene clays (Figure 6), with liquefaction potential of the broader residential area [58]. The maximum thickness of sediment layers reaches up to 130 m in the central part of the basin (Figure 5). Figure 5: (**a**) Microzoning map for the city of Durres (**b**) iso-depth contours of Durres down to geologic rock formations (modified from [30]). The aforementioned characteristics are also based on bore-hole data in an East-West [IV-IV] cross-section close to the port (Figure 6) and their physical-mechanical parameters given in Table 2. The position of several boreholes, especially the deepest one, BHA, with a maximum depth of about 120 m, is shown. This cross section was developed in the framework of the Durres seismic microzonation project [30] and has been enriched with geophysical MASW measurements in selected points. One of these points refers to the accelerometer station of Durres (DURR), where the MASW method was performed to estimate the shear wave velocity profile [59]. The measured point is located \(\sim\)70 m west of the DURR accelerometric station (white arrow in Figure 7). The IV-IV cross section passes through the location of the accelerometric station of Durres (DURR). Values of P and S-wave velocity and N\({}_{\text{SFT}}\) are given up to an 80 m depth profile (Figure 8).