Identification of submarine landslides in the Colombian Caribbean Margin (Southern Sinú Fold Belt) using seismic investigations

Abstract

Submarine landslides can be triggered by several processes and involve a variety of mechanisms. These phenomena are important sediment transport processes, but they also constitute a significant geohazard. Mapping of the southwestern Caribbean Sea using 3D seismic data has allowed identification of several submarine landslides in the Colombian Margin in the area dominated by the Southern Sinú Fold Belt (SSFB). A poststack depth-migrated seismic cube survey with a 12.5 by 12.5 m bin spacing was used to identify landslides in an area covering 5746 km2. Landslides were interpreted using a seafloor morphologic parameter identification process and the internal deformation of the slope-forming material, as seen from seismic data. A total of 93 landslides were identified and classified based on their movement styles as follows: 52 rotational, 29 translational, and 12 complex landslides. In addition, 12 distinct deformational zones and a zone of mass transport complex (MTC) were identified. Five different ground condition terrains were interpreted based on landslide type and distribution as well as in geologic structures and seismic reflection analysis. Two main processes seem to influence landslides in the study area. First is the folding and faulting involved in the SSFB evolution. This process results in oversteepened slopes that start as deformational zones and then fail as translational or rotational slides. Those individual landslides progressively become complex landslide zones that follow geologic structural orientation. Second is the continental shelf break erosion by debris flows, which fills in intraslope subbasins and continental rise with several MTCs. According to the results, risk of damage by landslides increases in distances shorter than 4 km along structural ridge foothills in the study zone.