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Lisbon has been affected by several moderate to strong earthquakes that caused considerable damage and produced significant economic and social impacts (e.g., the November 1st, 1755, earthquake). Studies on the potential damage due to a seismic event have been done considering Lisbon's moderate to high seismic hazard, but the seismic site effects have not yet been investigated at the city scale. The local ground conditions can locally modify the characteristics of surface seismic motion. Based on a multidisciplinary dataset composed of surface geology, a geotechnical database, and a geophysical database that compiles all the available geophysical tests carried out in Lisbon, an integrated approach to seismic ground characterisation was performed. A regression analysis of the shear-wave velocity values compiled in the geophysical database was done for each geological unit. The peak frequency distribution in the city, assessed from the ambient vibration measurements, showed a pattern in peak frequency variation. It decreases from the oldest to the most recent geological formations that outcrop in the SW-NE direction. Three zones based on peak frequency value distribution were proposed. An estimation of the impedance contrast depths was computed through two processes, considering the previous results: (i) the shallower contrast depth was assessed through a sharp variation of NSPT values available in the geotechnical database, and (ii) the deeper contrast depth was estimated based on geology data and deep borehole information. The results showed that for the upper ∼100 m of depth, a consistent relationship between the contrasts identified through different data was obtained, even if uncertainty increased with depth. • A multidisciplinary dataset-based contribution to seismic microzonation. • V S -depth equations defined for each geological formation. • Peak frequency distribution at the city scale. • Impedance contrast depth map based on an integrated approach. • Consistent relationship between the contrasts identified through different data. [ABSTRACT FROM AUTHOR]

Historically, Portugal has suffered the effects of several strong earthquakes. In particular, Lisbon and the south and southwestern Portuguese coast were affected by the largest known European earthquake on November 1st, 1755. It is well known that the local ground conditions strongly affect the seismic ground motion, modifying the signal's amplitude, duration, and frequency content, which induces large variability in the motion induced to buildings and infrastructures. Aware of this situation, the Lisbon Municipality promoted the development of a project to elaborate a new seismic microzonation map, based on a large geotechnical database and geological data. The Eurocode 8 ground classification based on the V S30 parameter was adopted as reference. However, the geotechnical database has a very small number of geophysical logs and is mainly composed of borehole data and SPT blows number. An expedited methodology was applied to determine the N 30 parameter, as a proxy of the V S30 parameter. Non-invasive field experiments (surface waves seismic profiles and HVSR performed with ambient vibrations) and data collected from independent geophysical reports were also used to check and validate the classification based on N 30. Because the distribution of the classified profiles was not uniformly distributed, the final microzonation map was obtained from the combination of the profile classification and the surface geology. • Seismic microzonation map based on large geotechnical database. • Automatic algorithm to classify each profile based on a proxy of V S30 EC8 ground classification. • The final zonation joins the profile classification with geological data. [ABSTRACT FROM AUTHOR]