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TitleGeotechnical characterization of a submarine landslide in Southwind Fiord, Baffin Island, Nunavut
AuthorMacquarrie, M; MacKillop, K; Normandeau, AORCID logo
SourceCanada-Nunavut Geoscience Office, Summary of Activities 2021, 2022 p. 47-55 Open Access logo Open Access
LinksOnline - En ligne
Alt SeriesNatural Resources Canada, Contribution Series 20210518
PublisherCanada-Nunavut Geoscience Office
Mediapaper; on-line; digital
File formatpdf
AreaSouthwind Fiord; Davis Strait; Baffin Island
Lat/Long WENS -62.3708 -62.3653 66.7792 66.7750
Subjectsmarine geology; surficial geology/geomorphology; geophysics; Nature and Environment; engineering geology; Science and Technology; Health and Safety; marine environments; coastal environment; fiords; landslides; mass wasting; slope stability; slope failures; slope stability analyses; marine sediments; clays; silts; marine sediment cores; geophysical interpretations; geophysical surveys; acoustic surveys, marine; sediment properties; plasticity; hydraulic conductivity; shear strength; Natural hazards; Infrastructures; Phanerozoic; Cenozoic; Quaternary
Illustrationslocation maps; geoscientific sketch maps; plots; profiles; tables
ProgramPublic Safety Geoscience Baffin Bay
Released2022 03 21
AbstractMost eastern Baffin Island communities are located in the near-shore areas of fiords in Baffin Bay, where submarine landslides represent a significant geohazard for offshore infrastructure and for coastal communities. Fiords have long been known for the occurrence of a wide variety of mass-wasting processes and have been designated as one of the major submarine landslide areas. Geotechnical characterization is an important component in developing a better understanding of the engineering behaviour of the marine sediments and constraining seabed slope stability analysis. Southwind Fiord, eastern Baffin Island, contains numerous slope failures identified from 2018 and 2019multibeam bathymetry surveys and was chosen for detailed seabed sampling in 2018 as a test site to understand the occurrence and triggers of such events. A comprehensive geotechnical testing program was undertaken on sediments from two piston cores collected offshore Southwind Fiord: one from a reference seabed site, and one from a site within a slope failure. The geotechnical test data were used to characterize the geotechnical properties of the seabed sediments, and to evaluate slope stability and seabed foundation conditions within the fiord. The sediments within the two sites identify as low- to high-plasticity, normally consolidated clayey silts. The compressibility of the sediments is moderate to high, ranging from0.36 to 0.73. Based on the data presented in this paper, the sediments have a low hydraulic conductivity (average of 6.0 x 0.000000001 m/s), typical for clayey silt, and the Mohr-Coulomb failure criteria (effective cohesion and angle of friction) average 0.6 kPa and 31.3°. An infinite slope stability analysis suggests the sediments are stable under gravitational loading up to a critical slope angle of 20°.
Summary(Plain Language Summary, not published)
Nunavut communities are mostly located in the near-shore areas of fiords in Baffin Bay, where submarine landslides represent a threat to coastal communities, either directly due to tsunami waves or indirectly by destroying seabed structures. Fiords in general are known for the occurrence of submarine landslides because of steep slopes. Measuring the seabed sediment properties is important in understanding the engineering behavior of sediments which is required for installation of structures, including seabed communication cables. In addition these properties can be used to determine the risk and cause of the submarine landslides. The Southwind Fiord, Baffin Bay contains many submarine landslides and was chosen for seabed sampling in 2018 as a test site to understand the engineering behavior of the seabed sediments and the cause of submarine landslides. A large laboratory geotechnical testing program was done on sediments collected from two piston cores; a reference seabed site and a site within a submarine landslide. Geotechnical testing included bulk density, Atterberg limits, grain size, consolidation and triaxial tests. This paper presents the geotechnical test results and an estimate of the stability of the seabed slope.

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