Arguments and methods in distinguishing storm and tsunami debris and the problem of paleo-tsunami dating

More than 100 years of tsunami research have produced over 2000 scientific papers on this phenomenon, but less than 3% deal with geomorphologic or sedimentologic relics of these powerful natural events. As a result of field research in 17 regions of the Caribbean and Southern Europe, it is discussed how it is possible to discern whether large boulders have been transported by hurricanes or tsunami. Observations of boulder size as well as horizontal and vertical distance to the shoreline are presented and their relation to soil development, vegetation or artificial structures as relative age indicators is discussed. The actual state-of-the-art formulas for the calculation of the transport capacity of hurricane/tsunami wave heights with respect to the movement of boulders are presented. A catalogue of arguments for the identification of relative ages of the boulder movement as well as the problems of absolute dating is added. Finally, the specific character of the tsunami catastrophe of Dec. 26th, 2004, in the northern Indian Ocean is emphasized.