GNGTS 2024 - Atti del 42° Convegno Nazionale

Session 2.2 GNGTS 2024 the risk results for 6 municipaliCes in the Etna area (Milo, Giarre, Riposto, Santa Venerina, Zafferana Etnea, Acireale) for a hypotheCcal reference scenario. Two days aper the Etna erupCon of 24 December 2018 (Alparone et al., 2020), a strong earthquake (M W 5.0) hit the lower south-eastern flank of the volcano, causing extensive damage in the area between the municipaliCes of Acireale and Zafferana, with over 1,100 homeless (Pessina et. Al, 2021). It represents the largest event occurred in the area in the last 70 years. The flank erupCon at the volcano started with an intense degassing from the summit craters, an opening of erupCve fissure with a lava flow that ended on December 27. The (hypotheCcal) Tephra and Lava scenarios were generated assuming that the 2018 erupCon was not interrupted, and significant values of input parameters were assumed in the simulaCon process to create realisCc scenarios of lava invasion and ash ground loads, which are sufficiently important to cause damage to buildings and infrastructure. Fig. 1 shows the seismic scenario of December 26 th 2018, and hypotheCcal scenarios for lava and tephra loads. More comprehensive studies are being published (Sandri et al.) Fig.1 – From lep to right: seismic scenario, represented in terms of EMS-98 Intensity, for the December 26, 2018 earthquake, and hypotheCcal scenarios for lava flow and tephra loads. 3. The risk scenarios Damage assessment was calculated for residenCal buildings. Using data collected by the Italian InsCtute of StaCsCcs (ISTAT, 2011), that are updated and spaCally detailed, residenCal buildings were classified as masonry, reinforced concrete (RC) and other construcCon type, according to the method illustrated in Dolce et al. (2021). For the assessment of the seismic vulnerability and damage we used the model of Lagomarsino et al. (2021) for masonry buildings and that of RosC et al. (2021) for RC ones. Since the new models use both pga values, it was necessary to develop an ad hoc conversion relaConship between EMS98 intensity and pga, for this type of event of volcanic origin in the Etna area. The new conversion relaConship is the following: