Submarine mass failures as tsunami sources: their climate control

Abstract

Recent research on submarine mass failures (SMFs) shows that they are a source of hazardous tsunamis, with the tsunami magnitude mainly dependent on water depth of failure, SMF volume and failure mechanism, cohesive slump or fragmental landslide. A major control on the mechanism of SMFs is the sediment type, together with its post-depositional alteration. The type of sediment, fine- or coarse-grained, its rate of deposition together with post-depositional processes may all be influenced by climate. Post-depositional processes, termed sediment ‘preconditioning’, are known to promote instability and failure. Climate may also control the triggering of SMFs, for example through earthquake loading or cyclic loading from storm waves or tides. Instantaneous triggering by other mechanisms such as fluid overpressuring and hydrate instability is controversial, but is here considered unlikely. However, these mechanisms are known to promote sediment instability. SMFs occur in numerous environments, including the open continental shelf, submarine canyon/fan systems, fjords, active river deltas and convergent margins. In all these environments there is a latitudinal variation in the scale of SMFs. The database is limited, but the greatest climate influence appears to be in high latitudes where glacial/interglacial cyclicity has considerable control on sedimentation, preconditioning and triggering. Consideration of the different types of SMFs in the context of their climate controls provides additional insight into their potential hazard in sourcing tsunamis. For example, in the Atlantic, where SMFs are common, the tsunami hazard under the present-day climate may not be as great as their common occurrence suggests.

Potential for a hazardous geospheric response to projected future climate changes

“…The potential for triggering geological and geomorphological hazards is also elevated, most notably as ice mass is lost from the great ice sheets, smaller ice caps and individual glaciers and ice fields. In Greenland and Antarctica, isostatic rebound as ice mass is reduced may result in increased seismicity (Turpeinen et al 2008;Hampel et al 2010), which may in turn trigger submarine landslides that could be tsunamigenic (Tappin 2010). In Iceland, Kamchatka and Alaska, melting of ice in volcanically and tectonically active terrains may herald a rise in the frequency of volcanic activity (Pagli & Sigmundsson 2008;Sigmundsson et al 2010) and earthquakes (Sauber & Molnia 2004;Sauber & Ruppert 2008).…”

“…With a volume of between 2500 and 3500 km 3 , the Storegga Slide is one of the world's largest landslides, and is widely regarded to have been triggered by a strong earthquake associated with the isostatic rebound of Fennoscandia (Bryn et al 2005). From the perspective of future hazard potential, it is noteworthy that the Storegga event generated a major tsunami (Tappin 2010), with tsunami deposits identified at heights above estimated contemporary sea level of 10-12 m on the Norwegian coast, more than 20 m in the Shetland Islands and 3-6 m on the coast of northeast Scotland (Bondevik et al 2005). A range of mechanisms capable of being driven by anthropogenic climate change are presented by Tappin (2010) as having the potential to contribute to the formation of submarine mass failures, including earthquakes and cyclic loading due to storms or tides.…”

“…Notwithstanding a gas-hydrate trigger, increased numbers of earthquakes may themselves be capable of triggering landsliding of piles of glacial sediment accumulated around the margins of the Greenland and Antarctic land masses. Such a mechanism has been shown to be important in triggering major submarine landslides in the postglacial period, the best known of which is the Storegga Slide, formed off the coast of Norway 8.1 ± 0.25 ka BP (Lee 2009;Tappin 2010). With a volume of between 2500 and 3500 km 3 , the Storegga Slide is one of the world's largest landslides, and is widely regarded to have been triggered by a strong earthquake associated with the isostatic rebound of Fennoscandia (Bryn et al 2005).…”

“…Notably, variations in ice and water load have been linked to fault rupture (Hampel et al 2007(Hampel et al , 2010, magma production and eruption (McNutt & Beavan 1987;McNutt 1999;Pagli & Sigmundsson 2008;Sigmundsson et al 2010) and submarine mass movements (Lee 2009;Tappin 2010). Elevated pore-water pressures are frequently implicated in the formation of subaerial and marine landslides (Pratt et al 2002;Tappin 2010). The geospheric response to such changes in environmental conditions at times of glacial-interglacial transition is expressed through the adjustment, modulation or triggering of a wide range of surface and crustal phenomena, including volcanic (e.g.…”

“…Anderson 1974;Davenport et al 1989;Costain & Bollinger 1996;Wu et al 1999;Wu & Johnston 2000;Hetzel & Hampel 2005) activity, marine (e.g. Maslin et al 1998;Day et al 1999Day et al , 2000Masson et al 2002;Keating & McGuire 2004;Maslin et al 2004;McMurtry et al 2004;Vanneste et al 2006;Quidelleur et al 2008;Lee 2009;Tappin 2010) and subaerial (Lateltin et al 1997;Friele & Clague 2004;Capra 2006) landslides, tsunamis (McMurtry et al 2004;Lee 2009), landslide 'splash' waves (Hermanns et al 2004), glacial outburst (Alho et al 2005) and rock-dam failure (Hermanns et al 2004) floods, debris flows (Keefer et al 2000) and gas-hydrate destabilization (e.g. Henriet & Mienert 1998;Maslin et al 2004;Beget & Addison 2007;Grozic 2009).…”