Reconstruction of past marine submersion events (storms and tsunamis) on the North Atlantic coast of Morocco

Abstract. The North Atlantic coast of Morocco has been affected historically by marine submersion events resulting from both storms and tsunamis and causing human and economic losses. The development of proactive adaptation strategies requires the study of these events over centennial to millennial timescales. Using a 2.7 m sediment core sampled from the Tahaddart estuary, we have been able to reconstruct past marine submersion events on this coastal area of Morocco over the last 4000 years. The high-resolution sedimentological and geochemical analysis conducted on this core allows us to identify 14 sediment layers attributed to marine high-energy events. The core was dated with isotopic techniques (¹³⁷Cs, ²¹⁰Pb_ex, ¹⁴C) and the outcomes reveal that three sediment layers are in connection with two major historical marine submersion events. The first layer mentioned as E1 seems to fit with the great Lisbon tsunami in 1755 CE (Common Era), an event dated for the first time on the Atlantic coast of Morocco. The other two layers referred as E13 and E14 were dated between 3464 and 2837 cal BP and correlated with marine submersion deposits found on Spanish and Moroccan coasts, which confirms the existence of a major high-energy event (around 3200 BP) similar to the one in 1755 CE.