Chapter 12 - Foraminifera in tsunami deposits

Abstract

The use of foraminifera in tsunami deposits is multifaceted and ranges from their straightforward use at identifying sediments on land that represent marine incursions to complex relations between foraminiferal assemblages in runup and backwash tsunami deposition on and offshore. Known historical or modern tsunami deposits are often used as a “proof of concept” to test the use of foraminifera in identifying certain characteristics of the tsunami itself. This could include determining the number of waves to sourcing the offshore wave excavation depths and transport distances that could be used to infer tsunami wave height. Just as important as understanding the bathymetry, geology, geomorphology, and climatology of the region, it is also paramount to develop an understanding of the distribution of foraminifera in the local environment. This modern distribution is fundamental to much of the research into tsunami and paleotsunami deposits. Tsunami deposits can be complex as they potentially source sediments and the foraminifera therein from open marine to freshwater and inland environments. Foraminifera within paleotsunami deposits have the added challenge of preservation potential as a result of the taphonomic processes occurring since the time of deposition. The number of studies that have completed thorough foraminiferal analyses of tsunami and paleotsunami deposits and the surrounding modern environment is growing, and new insights into their potential uses are still expanding.