Sedimentary features of tsunami deposits - their origin, recognition and discrimination : an introduction

The occurrence of numerous, recent, large tsunami suggests that they are a common natural event, yet tsunami deposits in the geological record are rare. This apparent anomaly may be due to a real infrequency of events and/or poor preservation potential but alternatively may be due to misidentification. Robust criteria for the discrimination of tsunami deposits from other sources such as storms is still lacking, establishing these criteria is essential if we are to improve our understanding of tsunami frequency over geological timescales. By this means we will improve the identification of tsunami hazard and improve risk assessment. This special issue focuses on tsunami deposits, identifying their characteristics and their discriminating features from other sources such as storms. Although perhaps not as common as other ‘event’ sediments, it is considered likely that a reappraisal of the geological record is required to place them in their representative context.