Multi-proxy Analysis of the AD 1755 Lisbon Tsunami Deposits in El Palmar de Vejer, Spain

Abstract

AbstractThe study area, El Palmar de Vejer, located in the Gulf of Cadiz in southwestern Spain, was severely struck by the AD 1755 Lisbon tsunami. El Palmar de Vejer was chosen as the study area due to the topographical setting, characterized by the flat alluvial floodplain, which has good preconditions as a sedimentary archive for tsunami deposits in order to gain a better understanding of the effects of the Lisbon tsunami based on previous studies and historical descriptions. The sedimentological and geochemical features indicate the processes of successive tsunami wash-overs and subsequent backwash and ponding conditions. An analysis of the major elements revealed a distinction between marine and terrestrial depositional environments. Using organic geochemistry, several different natural compounds were detected (e.g., n-alkanes and n-aldehydes), as well as some anthropogenic compounds (polycyclic aromatic hydrocarbons). The results suggest a differentiation between the AD 1755 tsunami deposit and the lagoonal background sediments, thus making it possible to identify tsunami processes. The results of this study analyzing the sedimentary archive provide strong evidence that a multi-proxy approach, with the inclusion of geochemical applications, can confidently detect tsunami deposits, distinguish them from the surrounding background sediments and subsequently characterize their internal structure and composition.KeywordsAD 1755 Lisbon tsunamiGulf of CadizGeochemical signaturesEl Palmar de VejerTsunami wave cycleMulti-proxy analysis