GNGTS 2019 - Atti del 38° Convegno Nazionale

GNGTS 2019 S essione 1.1 27 • class B: masonry buildings with bearing-walls of good quality, typically roughly dressed calcarenites, one to two stories, with squared stones and generally good mortar, sometime with RC slab floors and tie-rods (Fig. 2c). • class C: reinforced concrete (RC) buildings, two to four stories, especially in the outskirts built-up since the mid-1960s. These structures were rare and did not include any kind of earthquake-resistant design or reinforcement (Fig. 2d). Intensity assessment. We interpreted the collected information to produce a scenario in terms of cumulated intensity for every day of the sequence. In all, we evaluated 169 localities. On 14 January, 3 earthquakes with 4.7≥M w ≥5.1 produced substantial damage to class A buildings in Gibellina, Salaparuta and Poggioreale (Tab. 1): large cracks in most walls, failure of non-structural individual elements, a few partial collapse. This scenario is consistent with intensity 7 EMS-98. Very slight damage (I 5-6) occurred in Alcamo, Calatafimi, Camporeale, Menfi, Montevago, S. Margherita, S. Ninfa, Sambuca (Fig. 3a). On 15 January, a shock with M w 5.3 (01.33) was followed by the mainshock M w 5.7 (02.01) and other strong aftershocks (4.8≥Mw≥5.4). Gibellina and Salaparuta suffered the collapse of many of the buildings already damaged (I 9); Poggioreale and Montevago, that the day before Fig. 3 - Intensity maps referred to the cumulative effects of the strongest earthquakes occurred during the 1968 Valle del Belìce sequence.