The most recent megalandslides of the Canary Islands: El Golfo debris avalanche and Canary debris flow, west El Hierro Island

Abstract

Two major landsliding events have been identified west of the island of El Hierro: The El Golfo debris avalanche and the Canary debris flow. These landslides were identified from swath bathymetry, seismic reflection, and TOpographic PArametric Sonar (TOPAS) data obtained in December 1994 during a cruise on board the Spanish R/V Hesperides. The El Golfo debris avalanche originated subaerially on the western flank of the island of El Hierro and has an associated 150 km 3 rock debris deposit on the base of slope. The Canary debris flow, which dislocated some 400 km 3 of sediment, resulted from a different failure originated between 3200 and 3700 m depth at the base of slope of the island of El Hierro. According to the studied data set, its source area seems to have been covered by the El Golfo debris avalanche deposit. The triggering of the El Golfo debris avalanche (between 136 and 21 ka) is related to tensional stresses on the rift zones of the island. These rift zones control the emplacement and morphology of the landslide scar. In the Canary Islands, a relation between landslide ages and island ages can be established, indicating a link between subsidence history, age of shield phases, and giant landslides.