Flank stability and processes off the western Canary Islands: a review from El Hierro and La Palma

Abstract

SUMMARY: The morphological characterisation of the western submarine island flanks of El Hierro and La Palma differentiates four type-zones that may give new insights into the evolution of oceanic island slopes. The different type-zones result from the interplay between constructive volcanic processes, hemipelagic settling and volcano collapses. The latter results in massive debris avalanche deposits, which form large volcaniclastic aprons. In most cases, the headwall scarps are clearly exposed on the emerged part of the islands. The events that occurred in the youngest and westernmost islands of El Hierro and La Palma have vertical runouts exceeding 6,000 m and volumes that can reach several hundred km 3 . The landslide frequency for the entire Canaries is one major event per 90 ka. Triggering mechanisms are closely related to magmatic processes. The increase in the shear stress is directly linked with the forceful intrusion of magma along "ridge-rift" systems, while in the western Canary Islands it seems that the main process reducing shear resistance may be related to the rise in pore pressure due to hydrothermal circulation.

Submarine landslides of the Mediterranean Sea: Trigger mechanisms, dynamics, and frequency-magnitude distribution

“…The tectonically active margins of California with ~7% and Oregon with ~3% [ McAdoo et al ., ] present a significantly lower proportion. The volcanically dominated slopes around the Canary Islands present intermediate values with ~10% of its seafloor occupied by sediment gravity flows [ Urgeles et al ., ].…”

Turbidite record of frequency and source of large volume (>100 km3) Canary Island landslides in the last 1.5 Ma: Implications for landslide triggers and geohazards

“…However, Urgeles et al . [] cited an alternative age between 0.54 and 0.88 Ma for the El Tinor landslide.…”

“…[4] The Western Canary Island landslides have been shown to generate large debris avalanche deposits on the proximal submarine aprons (Figure 1a) [Holcomb and Searle, 1991;Masson, 1995, 1998;Ablay and H€ urlimann, 2000;Gee et al, 2001;Urgeles et al, 1999Urgeles et al, , 2001Masson et al, 2002]. These debris avalanches often disaggregate and generate turbidity currents that are deposited distally on the neighboring abyssal plain [Garcia and Hull, 1994;Garcia, 1996]; in this case, the Madeira Abyssal Plain [Watts and Masson, 1995;Masson, 1996;Wynn and Masson, 2003;Hunt et al, 2011].…”

Morphological and geological aspects related to large slope failures on oceanic islands

“…1). More than 20 huge volcanic landslides were detected during the last decades around this archipelago (Holcomb and Searle, 1991;Watts and Masson, 1995;Watts and Masson, 2001;Teide-Group, 1997;Funck and Schmincke, 1998;Urgeles et al, 2001). Eight of these events are situated on Tenerife Island and we selected the La Orotava at the north flank of Tenerife as the main test site during this study, due to the large amount of data available.…”