RRS "Charles Darwin" Cruise CD168, 02 Feb - 16 Feb 2005. Submarine landslides around the Cape Verde Islands

Abstract

Catastrophic large-scale landslides are a fundamental process in the formation of many oceanic islands. The main aim of cruise CD168 was to carry out a reconnaissance survey of the influence of landsliding on the Cape Verde islands, in the eastern central Atlantic, and to compare this with the known effects of landsliding on the Canary Islands. The data collected during RRS Charles Darwin Cruise, when combined with synthetic aperture radar imagery of the subaerial islands, show clear evidence for geologically young landslides off Fogo and Santo Antao, supporting the interpretation that these islands are the youngest and most active in the group. An extensive debris apron, covering an area of about 1000 km3, occurs to the east of Fogo, confirming the onshore amphitheatre as a landslide scar. Debris avalanche deposits are recognised to the north and south of Santo Antao, with at least two phases of geologically recent landsliding recognised to the south. The slopes of many of the older islands are deeply incised by submarine canyons, making recognition of old landslides difficult. However, preliminary analysis of slope profiles suggests that some palaeo-landslide areas are still recognisable