Numerical simulation of the tsunami generated by a past catastrophic landslide on the volcanic island of Ischia, Italy
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ORIGINAL RESEARCH PAPER
Numerical simulation of the tsunami generated by a past catastrophic landslide on the volcanic island of Ischia, Italy Stefano Tinti • Francesco Latino Chiocci Filippo Zaniboni • Gianluca Pagnoni • Giovanni de Alteriis
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Received: 10 April 2010 / Accepted: 13 November 2010 / Published online: 5 December 2010 Springer Science+Business Media B.V. 2010
Abstract The island of Ischia, Gulf of Naples, Italy, like many other volcanic islands is affected by mass failures, that are mainly related to secondary volcanic processes such as slope steepening and seismic shaking. The block resurgence of its main relief, Mount Epomeo, has been recognised to contribute cyclically to mass instability and cause landslides, that occasionally may reach the sea and start tsunamis. In this work we explore the consequences of the Ischia Debris Avalanche (IDA), a flank collapse that occurred in historical times, and involved the whole Mount Epomeo edifice including its submarine portion, and that may have caused gigantic sea waves affecting all the coasts of Ischia and of the Gulf of Naples. The IDA and the generated tsunami have been taken as the worst-case scenario for the occurrence of a new tsunami in the area. They have been simulated through numerical codes developed and maintained by the University of Bologna. The simulation shows that the IDA-induced tsunami attacks severely all the coasts of the Gulf of Naples with the highest waves obtained for the island of Ischia, the island of Capri and the peninsula of Sorrento. The propagation pattern of the IDA tsunami can be used to get hints on the impact that such an event may have had on early populations habiting Gulf of Naples, but also to get clues on the area that could be most
S. Tinti F. Zaniboni (&) G. Pagnoni Sector of Geophysics, Department of Physics, University of Bologna, Bologna, Italy e-mail: [email protected] F. L. Chiocci Department of Earth Sciences, University of Rome La Sapienza, Rome, Italy G. de Alteriis IAMC, CNR and GeoLab Marine Surveys, Naples, Italy
severely hit by a tsunami generated by a smaller-scale landslide that may occur in the same source zone. Keywords Ischia Debris Avalanche Numerical modelling Landslide Tsunami Gulf of Naples
Introduction Volcanic islands are widely recognised to be among the most propitious environments for tsunami generation, due to their tendency to flank instability and lateral failure (see review in Mc Guire et al. 1996). This is undoubtedly the case of the island of Ischia, which still is an active volcanic complex that borders to the north-west the Gulf of Naples (south-eastern Tyrrhenian Sea, Italy) together with Procida and the Phlegrean Fields polygenic volcanoes (Fig. 1). The continental shelf is well developed to the north and northwest of the island, with depths mostly lower than 100 m and slopes around 2–3, whereas it is nearly absent to the south where a very steep upper slope (up to 20) connects the island southern shore to a milder lower slope that starts at about
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