Tsunami boulder deposits - A strongly debated topic in paleo-tsunami research

Abstract

Research into boulder deposits by tsunamis and strong storms is still in its infancy. Tsunami provenience often is rejected for older deposits because boulders are not typical or important objects dislocated by tsunami events. However, this assumption is not supported by the physics of tsunami inundation flow. This paper focuses on the wide variety of environmental factors and field data that support boulder transport and deposition due to historical tsunami events. It considers the character of single boulders and boulder accumulations, as well as how dislocation age and sea-level history are interlinked. For historical events, methods to reconstruct environmental conditions such as shoreline character, boulder form and size during transport, preservation status, changes in sea level and, in particular, age of the dislocation event, and later impact processes are also important. Without such data, numerical modeling of erosional and depositional processes due to tsunamis is not conclusive.