Surficial geology and physical properties 18: slope: Verrill Canyon

Mosher, D C; Moran, K.; Zevenhuizen, J

doi:10.4095/210786

Cited by 3 publications

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“…There have been a number of expeditions on the Scotian Shelf and Slope to collect geotechnical data and recover samples for laboratory analysis [11,19,20]. The scope of work for this paper pertains to data from 51 cores collected from 1988 to 2004 on the Scotian Slope in water depths from 532 to 2490 mbsl ( Figure 2A).…”

Section: Sediment Coring and Physical Propertiesmentioning

confidence: 99%

“…It is the objective of this study, therefore, to adopt a geostatistical approach to assess the effect of spatial variability of soil properties on slope stability analysis. The near surface geological and geotechnical properties of the Scotian Slope have been studied for a number of decades [18][19][20] and therefore has a wealth of data from which to conduct and interpret this statistical analysis. While this analysis is limited to shallow sub-seabed conditions ( 12 m) due to the availability of samples and technological limitations, it is felt that the approach provides insight to spatial and temporal stability assessment in general.…”

Section: Introductionmentioning

confidence: 99%

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Assessing Submarine Slope Stability through Deterministic and Probabilistic Approaches: A Case Study on the West-Central Scotia Slope

et al. 2018

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A simplified geostatistical approach was adopted to assess the effect of spatial variability of soil properties on slope stability analysis in order to understand continental margin geologic processes and potential geohazards for an area of the central Scotian Slope, offshore Nova Scotia, Canada. The analyses are conducted on piston core samples, thus are restricted to ~12 m sub-seabed; however, the approach provides insight into the general effects of spatial and temporal variability. Data processing using geostatistics and assessment of spatial correlation are used to characterize the current dataset. A deterministic assessment was performed for both non-spatially averaged and spatially averaged core sections. The results indicate that the estimated factor of safety increased by about 30% when spatially averaged values were used. A probabilistic model is introduced to assess reliability of the slope. The approach makes use of estimates of both the mean and variance of input random variables (e.g., Su and γb). The model uses an exact probabilistic formulation for the total stress stability analysis and a Taylor series approximation for the effective stress stability analysis. In both cases, the mean and variance of the factor of safety are computed, leading to estimates of failure probability. The results suggest that the deterministic analysis is conservative with respect to slope reliability, although they do not lead to an estimate of the probability of failure. While these results indicate sediment instability is largely unlikely under static conditions, the reality is that many examples of submarine slope failure are observed in the geologic record. These results suggest that cyclic loading (earthquakes) or pre-conditioning factors (elevation of pore pressures) are critical for slope instability on the Scotian Slope.

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Section: Sediment Coring and Physical Propertiesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Assessing Submarine Slope Stability through Deterministic and Probabilistic Approaches: A Case Study on the West-Central Scotia Slope

et al. 2018

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“…Initial sedimentological assessment was presented by Mosher (1987) and some of the geotechnical framework is presented in Mosher et a/. (1991).…”

Section: Introductionmentioning

confidence: 99%

Late Quaternary sediment, sediment mass flow processes and slope stability on the Scotian Slope, Canada

Mosher

Moran²,

Hiscott

1994

Sedimentology

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The study area, just to the west of the Verrill Canyon on the Scotian Slope, eastern Canada, exhibits both large and small scale sediment mass movement features. Study of high resolution seismic reflection and sidescan sonar data shows that a large portion (approximately 70%) of the near surface sediment (<20 m) in the area has undergone erosion, rotational slumping and internal deformation. Remoulded sediment observed in physical properties profiles of piston cores and sediment deformation structures are further evidence of slumping. Small scale mass flow events are recorded by abundant turbidites and debris flow deposits noted in piston cores. Sediment physical properties are highly dependent on sediment type (lithofacies). Frequent facies changes, both temporally and spatially, make correlation between cores difficult. Although the small scale mass movement events correlate with glacial recession on the continental shelf and lower relative sea levels, the triggering mechanisms for the large scale events are less obvious. Slope stability analyses indicate that, at present, the seabed is stable. The most plausible explanation for large scale slope failures in this region are ground accelerations related to earthquake shock. Our analyses demonstrate that it is unlikely that large magnitude, distant earthquakes, such as those previously proposed in the Laurentian Slope Seismic Zone (LSP) model, could initiate failure of sediment in the study region. Our data support the interpretation that more frequent, lower magnitude earthquakes, closer to the study region, as previously proposed in the Eastern Slope Experimental Source Zone (ESX) model, are the likely causes of large scale slope failures. Furthermore, excess pore pressures resulting from shallow gas and/or high sedimentation rates during deglaciation contribute to slope failure.

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The appalachian glacier complex in maritime canada

Stea¹

2004

Developments in Quaternary Sciences

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Surficial geology and physical properties 18: slope: Verrill Canyon

Cited by 3 publications

References 0 publications

Assessing Submarine Slope Stability through Deterministic and Probabilistic Approaches: A Case Study on the West-Central Scotia Slope

Assessing Submarine Slope Stability through Deterministic and Probabilistic Approaches: A Case Study on the West-Central Scotia Slope

Late Quaternary sediment, sediment mass flow processes and slope stability on the Scotian Slope, Canada

The appalachian glacier complex in maritime canada

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