PSI - Issue 78

Matilde Natalizi et al. / Procedia Structural Integrity 78 (2026) 449–456

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4. Economic losses assessment of Norcia and Arquata del Tronto following the Central Italy 2016 earthquake The macroseismic fragility curves (Table 5) are used to carry out a seismic scenario analysis related to two municipalities affected by the 2016 Central Italy earthquake: Norcia and Arquata del Tronto, which suffered major shocks at different times but with comparable intensity (PGA). Following the event, 89.268 buildings were surveyed through AeDES forms, about 80% of which were masonry structures (Fig.1a) and among residential masonry buildings, nearly 80% were built before 1975 (Fig.1b). These data explain the extensive damage caused by the earthquake, due to the high vulnerability of the existing building stock. The analysis focuses exclusively on residential masonry buildings that fall under the structural typologies listed in Table 1 (Fig. 2b). Specifically, 1974 buildings were considered in Norcia and 1786 in Arquata del Tronto. In particular, the analysis is performed in two different ways. First, the economic losses (L tot (im)) evaluation is performed by assigning to each building, characterized by a certain level of damage, its specific % (M.D. n. 58/2017). The second analysis is performed according to the method described in Sect. 2 based on fragility curves. Therefore, the former refers to the assessment of losses according to the actual observed damage ( “ observed approach ” ), while the latter is a predictive assessment ( “ scenario approach ” ). Table 2 shows the average economic losses ( L tot ) for the two municipalities, expressed as a percentage of reconstruction cost, by considering the average ( ) recorded during the earthquake. As can be seen, the results from the scenario-based predictive approach are very close to those obtained from observed data. The difference between both is on average less than 4%, proving the effectiveness of using fragility curves in assessing the vulnerability of structures. This percentage refers to the average error across the entire municipalities. For individual typologies, the percentage error may be higher in some cases but still remains within acceptable limits.

Table 2. Comparison of economic losses for the municipalities of Norcia and Arquata del Tronto Observed approach N. of buildings [g] , [%] Norcia 1974 0.406 27.2% Municipality

, [%] 28.1% 45.9%

Scenario approach

Error [%]

3.4% -3.8%

Arquata del Tronto

1786

0.375

47.7%

The results reveal a significant difference in the economic losses: Norcia suffered less damage than Arquata del Tronto and neighbouring municipalities. This can be attributed to Norcia ’s history, characterised by a continuous evolution in seismic risk awareness and, consequently, in the adoption of preventive measures and construction regulations, as well as improvement plans that included interventions such as reinforced composite mortars (CRMs) or mortar injections, which improve the quality of masonry, the insertion of tie rods and the replacement of flexible

a)

b)

Fig. 1. a) Percentage distribution for construction material surveyed after the Central Italy 2016 earthquake; b) Percentage distribution of residential masonry buildings for construction period.