GNGTS 2024 - Atti del 42° Convegno Nazionale

Session 1.1 GNGTS 2024 Fig. 2 – Coeval sources reportng informaton and data on the 1952 seismic sequence along the S. Tecla fault. The number of localites cited in the documents is also indicated. Analysis and preliminary results Among the retrieved documents, we found of great interest some tables saved in the State Archive of Catania, compiled by the technicians of the Civil Engineers following the mainshock of 19 March. These tables provide the precise situaton of the cumulatve damage produced by the seismic sequence in the afected municipalites (Acireale, S. Venerina and Zaferana), classifed by ISTAT census sectons; the associated number of buildings per sectons is also indicated. In partcular, the percentages of damaged edifces are divided into three categories: totally unusable, partally unusable, usable even if damaged. This “operatve” level of damage was then associated with the grades of damage (D) expected in the EMS, as follows: totally unusable D4-5, partally unusable D3, usable D1-2. In order to defne the vulnerability classes of buildings prevailing in the damage area, we used photos and videos collected in the historical investgaton, together with the descriptons on the state of buildings provided in some technical reports. Since we worked at the scale of census sectons, the percentage of the diferent typologies of buildings in the 1950 was estmated according to Pessina et al. (2021) (Tab. 1). In this way, from the analysis of quantty and grade of damage for the diferent building vulnerability classes in each locality, it has been possible to assess the EMS intensity. Tab. 1 – Statstcal distributon of the EMS vulnerability classes vs buildings’ age (from Pessina et al., 2021).