Geomorphological signatures of known climatic extreme events and validation of theoritical emplacement approach: Boulders on Cuban low-lying Marine Terraces 

Abstract

To assess coastal hazard where Coastal boulder deposits (CBDs) are found, it is crucial to constrain the forces governing their emplacement: from either storms/tropical cyclones or tsunamis. Here we focus on the CBDs on the island of Cuba and the extreme climatic events responsible for their formation. Four sites are being studied to identify the CBDs produced during known hurricanes over the last fifty years.The selected CBDs are located on a low-lying coral reef terrace on the Cuban shore, emplaced by the Cuban hurricane of 1935, Lili hurricane of 1996 and Matthew hurricane of 2016. These meteorological events associated with reported geomorphological objects are analyzed to quantify the hydrodynamic parameters of such extreme events (maximum orbital velocity). Furthermore, the quantification of CBDs volume by stereophotogrammetry (using Agisoft Metashape Professional version 1.7.2) and CBDs density by water immersion method on samples allow us to use deterministic and theoretical approaches ( hydrodynamics equations of Nandasena et al., 2013, 2022 ) to assess the assumed associated hydrodynamic parameters (minimum flow velocity) responsible for the dislocation of the coral reef terraces and transport of the resulted boulders. Finally, we compare these velocities with ones  calculated from the meteorological  events to discuss the reliability of these approaches to determine the climatic or tsunamigenic origin of the past extreme waves from geomorphological analyses of CBDs.