Abstract
Subaqueous slopes are susceptible to a broad range of failure mechanisms and deformation styles, many of which are not well characterised. We undertook novel laboratory-based testing using a Dynamic Back-Pressured Shearbox on samples collected from an area subject to ongoing slope failures, situated on the upper slope of New Zealand's Hikurangi Margin, to determine how increases in pore water and gas pressures generate shallow mass movement. Using both water and nitrogen gas we observed similar responses in both cases, indicating that behaviour is dominated by the normal effective stress state regardless of pore-fluid phase. Shear-strain accumulation, representing landslide movement, shows a slow episodic pattern, in common with many shallow terrestrial landslides. Our results are relevant for landslides occurring in shallow near surface sedimentary sequences but have implications for deep-seated landslide behaviour. They suggest that once movement initiates at a critical effective stress, its rate is regulated through dilation and pore expansion within the shear zone, temporarily increasing effective stress within a narrow shear band and suppressing rapid shear. Consequently, under certain conditions, shallow submarine landslides (e.g. spreading failures) can undergo slow episodic movement which allows them to accumulate large shear strains without accelerating to catastrophic movement even when they are unconstrained.
Original language | English |
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Pages (from-to) | 99-107 |
Number of pages | 9 |
Journal | Geomorphology |
Volume | 329 |
DOIs | |
Publication status | Published - 15 Mar 2019 |
Bibliographical note
Funding Information:We thank Peter Barker, Stuart Read and Zane Bruce for laboratory support. Samples were provided by the National Institute of Water and Atmospheric Science (NIWA). Financial support has been provided through the GNS Science Strategic Development Fund, Marsden Fund Contract NIW1603 , GNS and NIWA Strategic Science Investment Funding and by the NERC / ESRC Increasing Resilience to Natural Hazards programme, grant NE/J01995X/1 , and NERC / Newton Fund grant NE/N000315 .
Funding Information:
We thank Peter Barker, Stuart Read and Zane Bruce for laboratory support. Samples were provided by the National Institute of Water and Atmospheric Science (NIWA). Financial support has been provided through the GNS Science Strategic Development Fund, Marsden Fund Contract NIW1603, GNS and NIWA Strategic Science Investment Funding and by the NERC/ESRC Increasing Resilience to Natural Hazards programme, grant NE/J01995X/1, and NERC/Newton Fund grant NE/N000315.
Publisher Copyright:
© 2019 Elsevier B.V.
Keywords
- Submarine slope movement mechanisms
ASJC Scopus subject areas
- Earth-Surface Processes