GNGTS 2014 - Atti del 33° Convegno Nazionale

GNGTS 2014 S essione 1.1 105 • in the town of Nardò variations of the water flow-rate of wells were observed, together with variations of chemical-physical properties of water: “ nel giorno di Mercoledì venti febbraio 1743…l’acque ne’ pozzi saltavano, e si riconcentravano…” (ASL 1743, Protocolli Notarili); • in the northern area of the island of Cephalonia (Greece) changes of chemical-physical properties of water were observed: “ The island of Cephalonia… in the 1736, 1743 and 1752… particularly in the northern part if island. It has been observed that strong odours of sulphur come up from wells ” (Saint Sauver, 1794, iii. 36, in Ambraseys, 2009); • in the locality of Castel Sant’Angelo (Corfù, Greece) the earthquake triggered a rockfall; • in the locality of ����� ������������� ������� �������� ���������� �� ����� �������� ���� Torre Sant’Emiliano tsunami deposits consisting of large boulders were observed, along the coastline, ���� � ������� ������ �� ����� �� � ��� � ��� �� �� ����� with a maximum weight of about 70 t � and a run up of about 11 m (Mastronuzzi et al. , 2007); • in the locality of ����� ����� ������� �������� ���������� �� ����� �������� ���� ��������� Torre Sasso tsunami deposits consisting of large boulders were observed, along the coastline, ���� � ������� ������ �� ����� �� � ��� � ��� �� �� ����� � � with a maximum weight of about 31 t and a run up of about 5 m (Mastronuzzi et al. , 2007). M����� ��� ��� ���� ��� ���������� �������� �� ��� ���� ������ ����� ������������� � ����� ainly for the last two localities strucked by the 1743 event, Torre Sant’Emiliano e Torre Sasso, well documented geomorphologic evidences of tsunami deposits (Mastronuzzi et al. , 2007) have been essential and firstly considered in order to assess the intensity values. All the collected data on the induced environmental effects have allowed us to review the MCS intensity values for some localities; as regards the town of Brindisi the intensity value has been further raised up from VIII to IX, due to the damage level and moreover to the tsunami phenomenon occurrence (Fig. 3). Intensity values of I � ���� ��������� �� ��� ��� ���� ����� ���� ���� �������� ��� ��� ≥ ��� ��� VIII according to the ESI 2007 scale have been assessed for the localities of Torre Sasso (Tricase) and Torre Sant’ Emiliano (Otranto), along the coastline of the Salento peninsula, as proved by the tsunami blocks dimensions; however, further constraining evidences have still to be uncovered. Preliminary results. The critical analysis of the documentary and historical sources, besides the geomorphologic evidences of effects due to the strong 1743 Salento earthquake, have allowed us to remodel a quite different scenario for this earthquake, leading to differently assessed intensity values for some localities, and also to new original estimations of intensity values for others. Actually, ������ ����������� strong earthquakes occurred in the far field respect to the Salento area, like the significant seismic events that have repeatedly hit Greece and Albania in the last centuries, have also caused heavy damages and serious tsunami effects in the Apulia region and Salento peninsula, despite the apparently low energy seismicity characterizing these areas, in comparison with other seismic areas of Italy. Fig. 3 – Map of the new intensity values revaluated in this paper for the 1743 Salento earthquake.