GNGTS 2016 - Atti del 35° Convegno Nazionale

60 GNGTS 2016 S essione A matrice Different damage distribution observed in the villages of Pescara del Tronto and Vezzano after the 2016 Central Italy Earthquake: some remarks A. Masi 1 , G. Santarsiero 1 , L. Chiauzzi 1 , M.R. Gallipoli 2 , S. Piscitelli 2 , L. Vignola 3 , J. Bellanova 2 , G. Calamita 2 , A. Perrone 2 , C. Lizza 3 , S. Grimaz 4 1 School of Engineering, University of Basilicata, Potenza, Italy 2 National Research Council - IMAA, Tito Scalo (PZ), Italy 3 National Association for Public Assistance (ANPAS), Marsicovetere (PZ), Italy 4 University of Udine, Italy Abstract. In the aftermath of the M L =6.0 central Italy earthquake occurred on August 24, 2016 the authors surveyed many damaged villages located in the epicentral area. Among them, some unexpected situations were found like, for example, the very different damage occurred to the villages of Vezzano and Pescara del Tronto (both districts of Arquata del Tronto). Despite these two villages are spaced just about 1300 m from each other, Pescara del Tronto undergoes very heavy damage with many collapses of masonry buildings and 48 fatalities, while Vezzano was subjected to very light damage to few buildings. In this paper possible causes of the different damage distribution are analysed from the engineering and geophysics point of view. Site geophysical investigations have been performed and their results are used to detect possible local effects responsible of increase of damage in Pescara del Tronto respect to Vezzano. Further, speditive visual inspections have been carried out in the two villages in order to detect possible significant differences in the vulnerability of their building stocks. Introduction. In the aftermath of the main event, the authors surveyed many damaged villages located in the epicentral area and some unexpected situations were found like, for example, the very different damage occurred to the villages of Vezzano and Pescara del Tronto (both districts of Arquata del Tronto). Despite these two villages are spaced just about 1300 m from each other, Pescara del Tronto undergoes to very heavy damage with many collapses of masonry buildings and 48 fatalities, whereas Vezzano was subjected to very light damage to few buildings. Observing the seismic history of the two villages, it is interesting to note that, during an earthquake occurred in the 1941 with the epicentre very close the village Vezzano, the two surveyed intensities were different for one degree of MCS scale, particularly VII MCS for Pescara del Tronto and VI MCS for Vezzano. The paper reports the results of site geophysical investigations, performed in order to detect possible local effects, and speditive visual inspections carried out in the two villages in order to detect possible significant differences in the vulnerability of their building stocks. Damage occurred in the villages of Pescara del Tronto and Vezzano and vulnerability comparison. In the first hours after the event, in the framework of the Copernicus Project (Copernicus, 2016) aerial images were taken in order to quickly evaluate the extent of damage in the villages prone to the epicentral area. The map related to Pescara del Tronto shows that 85% of the buildings suffered heavy damage or partial/total collapse, 10% suffered moderate damage, whereas just 5% of the buildings undergone no or slight damage. Damage observed in Vezzano is very different and no fatalities or injuries have been reported. Copernicus maps (Copernicus, 2016) refer that only one building out of about 70 reported heavy damage, while six buildings (less than 10%) suffered negligible to slight damage (Fig. 1). In Pescara del Tronto most of the structures are unreinforced masonry buildings of 2 to 3 storeys with some of them having 4 storeys. Few building are reinforced concrete. For what concern masonry buildings, quality of construction in Pescara del Tronto appears to be very poor with high inhomogeneity of stone elements. Moreover, it has been always possible to check the mortar quality that has very poor quality. The final judgment on the Pescara del Tronto masonry building’s vulnerability is very high. The vulnerability estimates for the village of Vezzano is harder due to the absence of damage and must be based only on what visible from outside the buildings. The survey revealed the absence of reinforced concrete buildings.