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TitleAssessing submarine slope stability through deterministic and probabilistic approaches: a case study on the west-central Scotia Slope
AuthorMacKillop, K; Fenton, G; Mosher, DORCID logo; Latour, V; Mitchelmore, P
SourceSubmarine landslides - assessing the stability of submerged slopes; by Urlaub, M (ed.); Geosciences vol. 9, issue 1, 2018 p. 1-18, Open Access logo Open Access
Alt SeriesNatural Resources Canada, Contribution Series 20180395
PublisherMDPI AG
Mediapaper; on-line; digital
File formatpdf
ProvinceNova Scotia; Eastern offshore region
AreaScotian Slope; Atlantic Ocean
Lat/Long WENS -63.6667 -60.3333 43.5000 41.5000
Subjectsmarine geology; surficial geology/geomorphology; mathematical and computational geology; engineering geology; marine sediments; muds; landslide deposits; sands; marine sediment cores; slope stability; slope stability analyses; slope failures; stress analyses; shear tests; landslides; debris flows; slumps; erosion; continental margins; continental slope; geostatistics; models; piston cores; bed load; earthquakes; pore pressures; channels; bulk density; shear strength; lithology; colour; correlations; Risk assessment; Methodology; Phanerozoic; Cenozoic; Quaternary
Illustrationslocation maps; geoscientific sketch maps; profiles; lithologic sections; tables; plots; graphs
ProgramOffshore Geoscience
Released2018 12 28
AbstractA 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 gamma-b). 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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