Fjord-flank collapse and associated deformation in Aysén Fjord, Chile

Abstract

Fjords are one of the submarine environments where slope failures are most common, mainly due to their steep terrestrial and submerged flanks and the rapid sediment deposition that usually takes place at their head and side-entry deltas (Hampton et al. 1996). Fjord-flank collapses, defined here as the destabilization and subsequent failure of the subaerial and/or submarine sections of the fjord flanks, and their associated tsunami and displacement waves, often triggered by a seismic shock, are known from the fjords of Norway, Alaska, Canada and Chile. Such events can endanger human population and activities (e.g. Huhnerbach et al. 2004). On 21 April 2007, a M w 6.2 earthquake triggered several subaerial and submarine landslides along the flanks of Aysen Fjord (Chilean Patagonia, 45.5° S). Some subaerial landslides eventually entered the fjord, generating waves with run-ups of several metres along the shoreline (Naranjo et al. 2009; Sepulveda & Serey 2009). Landslides and waves resulted in ten fatalities and damaged numerous salmon farms. The area has been studied in detail on two cruises, RV Don Este in 2009 (Van Daele et al. 2013) and BIO Hesperides (DETSUFA cruise) in 2013 (Lastras et al. 2013 …