Giant Quaternary landslides in the evolution of La Palma and El Hierro, Canary Islands

In the past, large morphological escarpments in the Canaries have been generally related to explosive and/or erosive processes. Recent onshore and offshore investigations drastically changed this interpretation, by providing evidence of the importance of giant lateral collapses in the evolution of the islands, especially in their earlier stages of growth. Giant landslide scars and deposits are readily observed both onshore and offshore in the younger, western Canaries, and seem to be a common feature of the development of the entire archipelago. At least one catastrophic collapse is apparent on La Palms: the Cumbre Nueva giant landslide, which occurred about 560 I;a ago. This collapse removed some 200 km(3) of central-western La Palma, forming a large embayment. Three successive giant landslides and evidence of an aborted attempt at another are seen in the island of El Hierro. The combined volume of those collapses (estimated at about 400-500 km(3)) considerably exceeds the present subaerial volume of the island (about 140 km(3)). Giant landslides and erosion during the past million years have removed more than half of the total subaerial volume of La Palma and El Hierro. (C) 1999 Elsevier Science B.V. All rights reserved.