The last phase of the Storegga Slide: simulation of retrogressive slide dynamics and comparison with slide-scar morphology

Gauer, Peter; Kvalstad, Tore J.; Forsberg, Carl Fredrik; Bryn, Petter; Berg, K.

doi:10.1016/j.marpetgeo.2004.10.004

Cited by 107 publications

(56 citation statements)

References 14 publications

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“…Based on high-resolution seismic profiles and close examination of the Storegga slide morphology, previous studies (e.g., Bryn et al 2005;Gauer et al 2005) showed that the failure pattern of this submarine slope is very similar to onshore large-scale landslides through sensitive clays, which are commonly encountered in eastern Canada and Scandinavia. However, unlike quick clay, which could be highly sensitive, offshore marine-glacimarine clays are generally moderately sensitive (DeGroot et al 2007).…”

Section: Modeling Of Post-peak Shear Strength Degradation Of Sensitivmentioning

confidence: 86%

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Modeling of large-deformation behaviour of marine sensitive clays and its application to submarine slope stability analysis

et al. 2016

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Post-slide investigations suggest that many large-scale submarine landslides occur through marine sensitive clay layers. A nonlinear mathematical model for post-peak degradation of undrained shear strength of sensitive clay is proposed based on experimental results. A method for estimation of model parameters is presented. Incorporating the model, an analytical solution is developed to examine possible mechanisms of large-scale submarine landslides. Analyses are performed for mild infinite slopes where the failure initiates from a "fully weakened zone" of soil having undrained shear strength lower than the shear stress acting parallel to the slope. The driving force, in excess of resistance, generated from the fully weakened zone is then transferred to the surrounding soil elements resulting in shear band formation due to strain-softening behaviour of sensitive clays. When the length of the fully weakened zone is greater than a critical length, catastrophic shear band propagation (self-driven without any additional external force) occurs, which could result in large-scale offshore landslides. A simple design chart is developed to calculate the critical length. Compared with a 2005 study by Puzrin and Germanovich based on a linear post-peak shear strength degradation model, the present study gives a conservative estimation of critical length for catastrophic shear band propagation.Key words: sensitive clay, large deformation, submarine landslides, shear band, undrained shear strength.Résumé : Les enquêtes post-glissement de terrain suggèrent que de nombreux glissements de terrain sous-marin à grande échelle se produisent à travers les couches d'argiles marines sensibles. Un modèle mathématique non linéaire de la dégradation post-pic de la résistance au cisaillement non drainée de l'argile sensible est proposé sur la base de résultats expérimentaux. Une méthode d'estimation de paramètres du modèle est présentée. Incorporant le modèle, une solution analytique est développée pour examiner les mécanismes possibles de glissements de terrain sous-marin à grande échelle. Les analyses sont effectuées pour des pentes infinies douces où l'échec est entamé à partir d'une « zone totalement affaiblie » du sol ayant une résistance au cisaillement non drainé inférieure à la contrainte de cisaillement agissant parallèlement à la pente. La force d'entraînement, au-delà de la résistance, générée à partir de la zone entièrement affaiblie est transférée aux éléments de sol environnant aboutissant en la formation de bandes de cisaillement en raison du comportement d'adoucissement à la déformation des argiles sensibles. Lorsque la longueur de la zone entièrement affaiblie est supérieure à une longueur critique, une propagation d'une bande de cisaillement catastrophique (auto-conduit sans aucune force externe supplémentaire) se produit qui pourrait entraîner des glissements de terrain en mer à grande échelle. Un graphique de conception simple est développé pour calculer la longueur critique. Par rapport à une étude réalisée e...

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Section: Modeling Of Post-peak Shear Strength Degradation Of Sensitivmentioning

confidence: 86%

“…Based on the above information, s up = 40 kPa is used for the marine clay layer. For the upper glacial clay, Gauer et al (2005) assumed s u = 25 kPa at the seabed increasing linearly at 2.4 kPa per metre depth. An average s u = 50 kPa is therefore assumed for the upper clay layer.…”

Section: Mathematical Formulationsmentioning

confidence: 99%

Modeling of large-deformation behaviour of marine sensitive clays and its application to submarine slope stability analysis

et al. 2016

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“…Numerical simulations can reproduce this retrogressive, back-stepping behavior (Gauer et al, 2005). Our code incorporates a rheological model based on a Bingham fluid with a history/strain dependent yield strength and consistency; the initial conditions prescribe a weak layer that eventually becomes the glide plane.…”

Section: Detailed Modeling Of Initial Fragmentation and Frontal Behaviormentioning

confidence: 99%

“…4 shows how simple extensions of a basic viscoplastic model reproduce many important aspects of clay-rich debris flows . Quite detailed two or threedimensional modeling of slab fracturing in the starting phase and of frontal behavior is also possible (Gauer et al, 2005), but requires a large numerical effort (Sect. 4.3).…”

Section: Introductionmentioning

confidence: 99%

Emerging insights into the dynamics of submarine debris flows

Elverhøi¹,

Issler

Blasio

et al. 2005

Nat. Hazards Earth Syst. Sci.

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Recent experimental and theoretical work on the dynamics of submarine debris flows is summarized. Hy-droplaning was first discovered in laboratory flows and later shown to likely occur in natural debris flows as well. It is a prime mechanism for explaining the extremely long runout distances observed in some natural debris flows even of over-consolidated clay materials. Moreover, the accelerations and high velocities reached by the flow head in a short time appear to fit well with the required initial conditions of observed tsunamis as obtained from back-calculations. Investigations of high-speed video recordings of laboratory debris flows were combined with measurements of total and pore pressure. The results are pointing towards yet another important role of ambient water: Water that intrudes from the water cushion underneath the hydroplaning head and through cracks in the upper surface of the debris flow may drastically soften initially stiff clayey material in the "neck" of the flow, where significant stretching occurs due to the reduced friction at the bottom of the hydroplaning head. This self-reinforcing process may lead to the head separating from the main body and becoming an "outrunner" block as clearly observed in several natural debris flows. Comparison of laboratory flows with different material composition indicates a gradual transition from hydroplaning plug flows of stiff clay-rich material, with a very low suspension rate, to the strongly agitated flow of sandy materials that develop a pronounced turbidity current. Statistical analysis of the great number of distinguishable lobes in the Storegga slide complex reveals power-law scaling behavior of the runout distance with the release mass over many orders of magnitude. Mathematical flow models based on viscoplastic material behavior (e.g. BING) successfully reproduce the observed scaling behavior only for relatively small clay-rich debris flows while granular (frictional) models fail at all scales. For very large release masses, hydroplan-ing or significant softening of the shear layer due to water in-Correspondence to: A. Elverhøi (anders.elverhoi@geo.uio.no) corporation must be invoked to recover the observed scaling behavior; a combination of both effects likely will give the most realistic description of the phenomenon. Detailed studies of the neck behavior and the compositional dependence of the material properties are needed to arrive at a quantitative model. Other related and important open questions concern the rheological model appropriate for sandy debris flows and the suspension rate from the dense body into the associated turbidity current.

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“…Normally, just a small shear distortion can significantly reduce the soil strength of an extra sensitive clay. Due to this "strain-softening" property, the existence of sensitive clay layers is very possibly a main cause of many large-scale submarine landslides that occurred on nearly flat continental slopes, e.g., the Storegga slide Gauer et al 2005;Kvalstad et al 2005;Dan et al 2007;Locat et al 2014;Dey et al 2016). For this reason, many scientists had proceeded to study sensitive clay.…”

Section: Shear Zone Introductionmentioning

confidence: 99%

Frictional heating lubrication for submarine landslide

Chen¹,

Yang²,

Hwung³

2018

Terr. Atmos. Ocean. Sci.

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Given a large block of fine-grained sediment that overlies a 1° continental slope, if the entire sediment deposit is shaken by an earthquake to slide down the slope with an initial velocity (referred to as "submarine landslide" hereinafter), our block model showed that the whole deposit can continuously slide downslope with the "help" of basal frictional heating. In theory, basal Coulomb friction can generate a thermal internal energy in the basal shear zone of landslides (called "frictional heating"), the increasing temperature activating two mechanisms. One mainly decreases the Terzaghi effective normal stress of the landslides and the other decreases the Coulomb friction coefficient. Combining these two mechanisms can effectively decrease the basal frictional resistance of the landslides increasing the mobility of the landslides on gentle slopes (entitled as "frictional heating lubrication"). As shown in our calculations, frictional heating increases with the increase of the initial downslope velocity but decreases with the increase of the shear zone thickness.

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The last phase of the Storegga Slide: simulation of retrogressive slide dynamics and comparison with slide-scar morphology

Cited by 107 publications

References 14 publications

Modeling of large-deformation behaviour of marine sensitive clays and its application to submarine slope stability analysis

Modeling of large-deformation behaviour of marine sensitive clays and its application to submarine slope stability analysis

Emerging insights into the dynamics of submarine debris flows

Frictional heating lubrication for submarine landslide

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