Coastal Submarine Failures in the Strait of Georgia, British Columbia: Landslides of the 1946 Vancouver Island Earthquake*

Mosher, D.; Monahan, P A; Barrie, J. Vaughn; Courtney, R C

doi:10.2112/1551-5036(2004)20[277:csfits]2.0.co;2

Cited by 13 publications

(2 citation statements)

References 14 publications

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“…Notable examples of earthquake-induced instabilities are the following (see also Chillarige et al 1997;Seed 1968): the Grand Banks slide (1929), Newfoundland, Canada (Piper et al 1999); Vancouver Island slides (1946), British Columbia, Canada (Mosher et al 2001); the Valdez slide (1964), Alaska, United States (Lemke 1967); the Saguenay Fjord slide, Quebec, Canada (Urgeles et al 2001); the Storegga slide, Norway (e.g., Bugge et al 1987); the Karmsundet and Skudenesfjorden slides, Norway (Boe et al 2000); and the Humboldt slide, northern California, United States (Gardner et al 1999).…”

Section: Submarine Retrogressive Failuresmentioning

confidence: 99%

Finite element simulation of seismically induced retrogressive failure of submarine slopes

Azizian¹,

Popescu²

2005

Can. Geotech. J.

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Retrogressive failures have been reported for both offshore and onshore slopes subjected to various triggering mechanisms. As a result of large spatial extension of the failure, the retrogression phenomenon leads to significantly increasing damage and may affect facilities located far away from the original slope. The mechanisms of such failures are not fully understood, and reports of analyses are rather scarce. To simulate earthquake-induced retrogressive submarine slope failures and to better understand the mechanisms involved, the element removal capabilities of a finite element program are used to model a soil mass that fails and then flows away, causing upper parts of the slope to fail retrogressively, as a result of the loss of support. It is explained how an initial failure leads to subsequent failures of a flat seafloor. Effects of a shallow silt layer and of a gently sloping seafloor on the extension of retrogression in a sandy seabed are also studied. It is found that the extension of failure increases significantly because of a gentle seafloor slope and (or) the presence of a silt layer.Key words: retrogressive submarine failure, seismic liquefaction, finite elements.

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Section: Submarine Retrogressive Failuresmentioning

confidence: 99%

Finite element simulation of seismically induced retrogressive failure of submarine slopes

Azizian¹,

Popescu²

2005

Can. Geotech. J.

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“…Subaqueous landslides are important sediment-transport processes, reshaping passive and active ocean margins (McAdoo et al, 2000;Hühnerbach et al, 2004;Talling et al, 2014;Moscardelli and Wood, 2016;Clare et al, 2018), marine coastal settings (Mosher et al, 2004), fjords (Parsons et al, 2014;Bellwald et al, 2016) and lake basins (Moernaut and De Batist, 2011;Sammartini et al, in press). Due to their potential to trigger large tsunamis, they can constitute significant geohazards for coastal populations and infrastructure (Tappin et al, 2001).…”

Section: Introductionmentioning

confidence: 99%

The subaqueous landslide cycle in south-central Chilean lakes: The role of tephra, slope gradient and repeated seismic shaking

Moernaut

Daele

Heirman

et al. 2019

Sedimentary Geology

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Subaqueous landslides are common features at active and passive ocean margins, in fjords and lakes. They can develop on very gentle slope gradients (<2°) and the presence of sandy tephra layers seems to facilitate the development of translational failure. Despite numerous investigations, it remains elusive how different slope preconditioning factors act and interact over time and how different triggering mechanisms can lead to slope failure. In settings of low to moderate seismicity, stratigraphic sequences with sublacustrine masstransport deposits (MTDs) have successfully been used for constructing prehistorical earthquake catalogues.In high seismicity areas, it is inferred that not all strong earthquakes succeed in triggering landslides on the investigated slope segments, and MTD records do not fully represent their complete recurrence pattern.Here, we present the spatio-temporal distribution of MTDs in two large glacigenic Chilean lakes (Villarrica and Calafquén) based on a detailed seismic-stratigraphic analysis and several radiocarbon-dated piston cores (up to 14 m long). We find a strong influence of slope gradient on the occurrence and volume of landslide 2 events; i.e. most (small) landslides take place on slopes of 5-20°, whereas the few large (potentially tsunamigenic) landslides exclusively occur on slopes of <4°. Liquefaction of sandy tephra layers facilitates the development of thin (<0.5 m) in-situ deformations during earthquake shaking. When sandy tephra layers get progressively buried, liquefaction becomes unlikely, but repeated excess pore pressure transfer to overlying units facilitates the development of translational sliding. The occurrence of voluminous landslides seems to follow a "landslide cycle" which starts with the deposition of a tephra layer and the development of in-situ deformations directly on top. Once the slope sequence reaches a critical thickness, the end of the cycle is indicated by incipient scarp development, and subsequent major sliding event(s). The duration of the landslide cycle is defined by the rate of gradual sedimentation, but may be affected by sudden geological events (e.g., volcanic eruptions), expediting the end of the cycle. Despite the many methodological challenges inherent to the construction of a MTD stratigraphy, we propose that well-dated multiple MTD events can be used as positive evidence to strengthen and specify the regional paleoseismic record, concerning the largest events in a high-seismicity region. This method is most successful when targeting the base of relatively steep slopes (5-20°) with frequent, minor landsliding, and complementing this with seismic-stratigraphic analysis of fluid-escape features and correlation with distal turbidite records.

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Submarine Mass Movements and Their Consequences

Yamada

Kawamura

Ikehara³

et al. 2010

Submarine Mass Movements and Their Consequences

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Coastal Submarine Failures in the Strait of Georgia, British Columbia: Landslides of the 1946 Vancouver Island Earthquake*

Cited by 13 publications

References 14 publications

Finite element simulation of seismically induced retrogressive failure of submarine slopes

Finite element simulation of seismically induced retrogressive failure of submarine slopes

The subaqueous landslide cycle in south-central Chilean lakes: The role of tephra, slope gradient and repeated seismic shaking

Submarine Mass Movements and Their Consequences

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