Sedimentary impacts of Holocene tsunami events from the intra-Americas seas and southern Europe: a review

Field research conducted since the year 2000 in southern Europe (Portugal, Spain, Greece, Cyprus and Turkey) and on several islands of the Intra-Americas Seas (Aruba, Curaçao, Bonaire, Grenada, St. Lucia, Barbados, Guadeloupe, St. Martin/St. Maarten, Anguilla, Eleuthera and Long Island) has indicated a great number of so far unknown but strong tsunami events of Younger Holocene age. Their run-up values are significantly higher than those of historical tsunami in the Caribbean (since 1498 AD) or those mentioned in the Mediterranean catalogues, and, in view of the fact that some of them extended over many hundred kilometres of coastline, they may well be placed in the category of mega-tsunami events. A very typical signature of nearly all of these tsunami are large boulders up to 200 t, dislocated far inland and on higher ground well outside the reach of hurricane or storm waves. A large number of absolute datings by radiocarbon and Electron Spin Resonance (ESR) show repetition times of several hundred to more than 1,500 years, but nevertheless tsunami events present significant risks to growing populations, visitors and to the coastal infrastructure. Should a tsunami with the energy comparable to the described ones occur in future, a major catastrophe will result. In this paper a short summary of the results from the different regions is presented to act as comparison material with the results of the mega-tsunami in the Indian Ocean on Dec., 26th, 2004.