The seismic vulnerability assessment of a building requires a comprehensive knowledge of both building structural features and soils geophysical parameters. To achieve a vulnerability assessment at the urban scale a large amount of data would be necessary, with a consequent involvement of time and economical resources. The aim of this paper is hence to propose a simplified procedure to evaluate the seismic vulnerability of urban centres and possible seismic damage scenarios in order to identify critical areas and/or building typologies to plan future actions of seismic risk mitigation and prevention. The procedure is applied to the outstanding case study of the city of Florence. The research is based on the definition of major building typologies related to construction periods and type of the structural system (masonry or reinforced concrete), the identification of a set of sample buildings, the analysis of the dynamic behaviour and the evaluation of a vulnerability index with an expeditious approach. The obtained results allow to define potential vulnerability and post-event damage scenarios related to the expected levels of peak ground acceleration.

Abstract. This work deals with the evaluation of the seismic vulnerability of urban

Dynamic identification is considered a powerful technique for testing the conservation status of buildings as their natural frequencies, damping and modal shapes are directly related to their rigidity and structural integrity. This issue is of crucial interest when historical structures are in area of high seismic level, as SanSepolcro city which has experienced earthquakes up to a maximum intensity of I max = X MCS scale. The dynamic response is suitable for ancient structures because is performed by measuring ambient vibrations instead of actively shaking the building. The results obtained from dynamic tests might be used to validate the assumptions used in numerical modeling in order to reduce the uncertainties related to the soil-structure interaction and to the structural parameters. In this framework, we show how an automatic identification procedure can track in real-time the dynamic response of the museum in Sansepolcro (Italy) using operational modal analysis (OMA). The dynamic characteristics, of the SanSepolcro museum and the wall supporting the mural painting of Resurrection of Christ, were identified by installing a temporary network of 10 seismic sensors. The OMA technique was performed using enhanced frequency domain decomposition (EFDD) which has allowed to detect the first four modal shapes, damping and structural frequencies. The dynamic characteristics were used to calibrate a more realistic and reliable 3D-FEM numerical model. Integrating, the results of the dynamic indetification with 3D-FEM model analysis, has provided important information to understand the complicated system of connections between the existing walls.

While a landslide at the volcanic island of Stromboli (Aeolian Islands, Italy) in December 2002 created a tsunami with a run-up of 10.9 m, two paroxysmal eruptions in the summer of 2019 caused a tsunami with an amplitude of 40 to 20 cm. All three events required rapid, spontaneous emergency evacuations of the beach zone as the time between tsunami generation and impact is around 4 min. These conditions thus require a special consideration of the issue of evacuation capabilities on the island in the event of a volcanogenic tsunami. The purpose of this paper is thus to (i) determine pedestrian evacuation times from high-risk coastal areas to safe zones, (ii) to assess building evacuation ease, and (iii) determine emergency evacuation plans (for buildings and coastal zones). For this purpose, we created a GIS-based risk analysis/mapping tool that also allowed macroscopic evacuation modelling. In our case, the high-risk zone to be evacuated involves an area extending to 10 m a.s.l. and involving 123 individual buildings over an area of 0.18 km2. The results show that 33% of the buildings can be evacuated in 4 min, and that a 10-min warning time is required for a complete and well-distributed evacuation whereby the population is evenly distributed between all evacuation exits to avoid the potential for congestion. Initial interviews of residents in the at-risk zone reveal a high level of awareness and a desire for personalized evacuation scenarios.

The seismic vulnerability assessment of a city is usually based on buildings’ characteristics, underground geophysical properties, socio-economic activities, and population density. This research highlights the value of a complete and manageable database for large-scale seismic vulnerability assessment of urban areas: such databases are often missing or partially developed for the majority of Italian cities. This study is based on the creation of a GIS database containing useful information to identify and valuate some indicators of seismic vulnerability in order to understand an earthquake’s effect for the actual configuration of a city. This system could be a growing source of information on cities and, if used in the proper way, a useful tool for monitoring, for seismic vulnerability assessment, and for spatial urban planning. The experience gained in this field of application can be transferred to other situations, both for the procedures and the workflow system.