GNGTS 2021 - Atti del 39° Convegno Nazionale

273 GNGTS 2021 S essione 2.2 Five urban sectors have been identified: C01 (Historical centre), C02 (Expansion zone), C03 (Calda), C04 (Agromonte Mileo) and C05 (Agromonte Magnano). Nevertheless, in the specific case, the homogeneous urban sector named C01 (Historical centre) has been examined. It is composed of 1075 buildings erected in aggregate configuration. The prevailing construction type is a masonry structure made of rough rounded stone (detected in 75% of the cases), which is called MUR1, an acronym used according to the technical indications provided by the CARTIS form. The other construction classes detected in the study area are MUR2 (regular masonry with squared or brick stones, 14%) and CAR1 (reinforced concrete, 4%). The statistical data referred to the buildings of the C01 sector are presented in Fig. 1. For the quantification of the observed damage, the Damage Probability Matrices, DPM, have been processed considering the real damages derived from the 1980 earthquake, which have been detected during the on-site inspection phase. The results depicted in Fig. 1 have highlighted that in the analysed urban sector C01, 26% of the buildings have no damage (D0), 40% slight damage (D1), 25%moderate damage (D2), 8% substantial damage (D3) and, last, 1% near collapse (D4). Fortunately, no building reaches the damage threshold D5 (collapse). Moreover, to assess the seismic vulnerability of buildings grouped in aggregate condition, it has been used a specific vulnerability form proposed (Chieffo and Formisano, 2020), specifically conceived for clustered buildings. From the acquired vulnerability scenario, most of the buildings surveyed (85% of the cases) are associated with a vulnerability index between 0.4 and 0.6 (medium vulnerability), while only 5% of the sample have vulnerability index enclosed in the range [0.6-0.8], which is associated to a medium-high expected vulnerability. Contrary, recent buildings (7% of the cases), erected after 1972, have a medium-low vulnerability index (0.2<VI<0.4). Furthermore, the propagation of the seismic motion has been described according to the proper intensity prediction equation model (IPE) proposed by Crespellani and Garzonio (1997). Therefore, the DPMs have been calculated based on the damage scenarios achieved by varying both magnitudes (4, 5, and 6.5) and epicentre distances (from 10 km to 30 km), according to the hazard disaggregation map proposed by the National Institute of Geophysics and Volcanology (INGV) (Locati, 2016) for the municipality of Latronico. Instead, the predictive DPMs have been derived from the binomial distribution law of the calculated damage (Zuccaro et al., 2021). In the worst-case scenario, corresponding to Mw = 6.5 and site-source distance of 10 km, 64% of the buildings reached a damage threshold D3 (significant damage). This damage level has been derived from the Fig. 1: Main characteristics of buildings surveyed in the urban sector C01.