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Characterisation of shallow overpressure in consolidating submarine slopes via seismic full waveform inversion

Characterisation of shallow overpressure in consolidating submarine slopes via seismic full waveform inversion
Characterisation of shallow overpressure in consolidating submarine slopes via seismic full waveform inversion

Pore pressures higher than hydrostatic correspond to localized reductions of the level of shear stress required to induce lateral mass movement in a slope, and therefore play a key role in preconditioning submarine landsliding. In this paper, we investigate whether multi-channel seismic reflection data can be used to infer potentially destabilizing pore-pressure levels at a resolution and sensitivity useful for in-situ slope stability characterization. We simulate the continuous deposition of sediment on consolidating slopes in two scenarios, with combinations of sedimentation rate and permeability distribution leading to disequilibrium compaction. Ultra-high-frequency (UHF; 0.2–2.5 kHz) seismic reflection data are computed for each model and a stochastic full waveform inversion (FWI) method is used to retrieve the sub-seabed properties from the computed seismograms. These are then interpreted as time–depth variations in the effective stress (σ′) regime, and therefore local overpressure ratio and factor of safety, using a combination of p-wave velocity to σ′ transforms. The results demonstrate that multi-channel UHF seismic data can provide valuable constraints on the distribution of physical properties in the top 50 m below seabed at a sub-metric scale, and with a sensitivity useful to infer destabilizing excess pore pressure levels.

1470-9236
366-377
Provenzano, Giuseppe
076fb0cd-74db-4b62-bc0b-afffbe442cc4
Zervos, Antonios
9e60164e-af2c-4776-af7d-dfc9a454c46e
Vardy, M.E.
2826320d-5f6d-444b-96e2-827a534f0531
Henstock, Timothy
27c450a4-3e6b-41f8-97f9-4e0e181400bb
Provenzano, Giuseppe
076fb0cd-74db-4b62-bc0b-afffbe442cc4
Zervos, Antonios
9e60164e-af2c-4776-af7d-dfc9a454c46e
Vardy, M.E.
2826320d-5f6d-444b-96e2-827a534f0531
Henstock, Timothy
27c450a4-3e6b-41f8-97f9-4e0e181400bb

Provenzano, Giuseppe, Zervos, Antonios, Vardy, M.E. and Henstock, Timothy (2020) Characterisation of shallow overpressure in consolidating submarine slopes via seismic full waveform inversion. Quarterly Journal of Engineering Geology and Hydrogeology, 53 (3), 366-377. (doi:10.1144/qjegh2019-019).

Record type: Article

Abstract

Pore pressures higher than hydrostatic correspond to localized reductions of the level of shear stress required to induce lateral mass movement in a slope, and therefore play a key role in preconditioning submarine landsliding. In this paper, we investigate whether multi-channel seismic reflection data can be used to infer potentially destabilizing pore-pressure levels at a resolution and sensitivity useful for in-situ slope stability characterization. We simulate the continuous deposition of sediment on consolidating slopes in two scenarios, with combinations of sedimentation rate and permeability distribution leading to disequilibrium compaction. Ultra-high-frequency (UHF; 0.2–2.5 kHz) seismic reflection data are computed for each model and a stochastic full waveform inversion (FWI) method is used to retrieve the sub-seabed properties from the computed seismograms. These are then interpreted as time–depth variations in the effective stress (σ′) regime, and therefore local overpressure ratio and factor of safety, using a combination of p-wave velocity to σ′ transforms. The results demonstrate that multi-channel UHF seismic data can provide valuable constraints on the distribution of physical properties in the top 50 m below seabed at a sub-metric scale, and with a sensitivity useful to infer destabilizing excess pore pressure levels.

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qjegh2019-019_accepted - Accepted Manuscript
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More information

Accepted/In Press date: 16 January 2020
e-pub ahead of print date: 22 January 2020
Published date: 13 March 2020
Additional Information: Accepted today, DOI is not yet live

Identifiers

Local EPrints ID: 437241
URI: http://eprints.soton.ac.uk/id/eprint/437241
ISSN: 1470-9236
PURE UUID: 1c509e84-8f8a-4fce-8f16-8bd7b8b1a49b
ORCID for Antonios Zervos: ORCID iD orcid.org/0000-0002-2662-9320
ORCID for Timothy Henstock: ORCID iD orcid.org/0000-0002-2132-2514

Catalogue record

Date deposited: 22 Jan 2020 17:32
Last modified: 26 Nov 2021 06:54

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Contributors

Author: Giuseppe Provenzano
Author: Antonios Zervos ORCID iD
Author: M.E. Vardy

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