Submarine geomorphology of the archipelago of San Andres, Providencia and Santa Catalina (western Caribbean)

Javier Idárraga-Garcia 1, Jacqueline García-Varón 2 and Hermann León 3

1 Universidad del Norte, Departamento de Física y Geociencias, Barranquilla, Colombia

2 Consultora, Bogotá, Colombia

3 Dirección General Marítima, Bogotá, Colombia

Recent acquisition of multibeam bathymetric data in western Caribbean allowed illuminating for the first time the submarine morphology of the Archipelago of San Andres, Providencia and Santa Catalina (ASAPSC), and surrounding areas. Our results show that the nine islands of the archipelago (San Andres, Providencia, Albuquerque, Este-Sureste, Roncador, Quitasueño, Serrana, Serranilla and Bajo Nuevo) correspond to the emerged portions of a belt of volcanic edifices extending along the ASAPSC seafloor. Overall, the submarine slopes are characterized by having steep flanks that extend to depths greater than -2000 m and are frequently cut by linear gullies and canyons. The submarine volcanic buildings are aligned in specific directions, parallel to the trends of the main fault systems in the area, indicating that the genesis and evolution of the archipelago have been strongly influenced by the interplay between volcanism and tectonics. Moreover, the presence of several pull-apart basins (Providencia, Albuquerque, Nutibara, Cunas and Guambiano depressions) related to S-shaped releasing bends in the Albuquerque-Providencia, Pedro and Serrana fault systems evidences that an intraplate transtensional tectonics is currently operating in this sector of the Caribbean plate. We propose that the ASAPSC belongs to the Northwestern Caribbean Volcanic Province (NCVP), which corresponds to a province made of an oceanic crust highly affected by volcanism sandwiched between a block composed of continental crust (Upper Nicaraguan Rise) and a block underlain by a CLIP-type to normal oceanic crust (Colombia Basin). Finally, the identification of massive debris avalanche deposits and large-scale bedforms shows that mass wasting processes have been common in the most recent history of the ASAPSC. This implies that collapses of the seamount flanks and the subsequent generation of tsunamis should be considered as a new threat to the coastal zones of the western Caribbean Sea.

  • Javier Idárraga-Garcia, Jacqueline García-Varón, Hermann León