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Decimetric-resolution stochastic inversion of shallow marine seismic reflection data; dedicated strategy and application to a geohazard case study

Decimetric-resolution stochastic inversion of shallow marine seismic reflection data; dedicated strategy and application to a geohazard case study
Decimetric-resolution stochastic inversion of shallow marine seismic reflection data; dedicated strategy and application to a geohazard case study
Characterisation of the top 10-50 m of the subseabed is key for landslide hazard assessment, offshore structure engineering design and underground gas-storage monitoring. In this paper, we present a methodology for the stochastic inversion of ultra-high-frequency (UHF, 0.2-4.0 kHz) pre-stack seismic reflection waveforms, designed to obtain a decimetric-resolution re- mote elastic characterisation of the shallow sediments with minimal pre-processing and lit- tle a-priori information. We use a genetic algorithm in which the space of possible solutions is sampled by explicitly decoupling the short and long wavelengths of the P-wave velocity model. This approach, combined with an objective function robust to cycle skipping, outperforms a conventional model parametrisation when the ground-truth is offset from the centre of the search domain. The robust P-wave velocity model is used to precondition the width of the search range of the multi-parameter elastic inversion, thereby improving the efficiency in high dimensional parametrizations. Multiple independent runs provide a set of independent results from which the reproducibility of the solution can be estimated. In a real dataset acquired in Finneidfjord, Norway, we also demonstrate the sensitivity of UHF seismic inversion to shallow subseabed anomalies that play a role in submarine slope stability. Thus, the methodology has the potential to become an important practical tool for marine ground model building in spatially heterogeneous areas, reducing the reliance on expensive and time-consuming coring campaigns for geohazard mitigation in marine areas.
0956-540X
1683-1700
Provenzano, Giuseppe
076fb0cd-74db-4b62-bc0b-afffbe442cc4
Vardy, Mark E.
8dd019dc-e57d-4b49-8f23-0fa6d246e69d
Henstock, Timothy J.
27c450a4-3e6b-41f8-97f9-4e0e181400bb
Provenzano, Giuseppe
076fb0cd-74db-4b62-bc0b-afffbe442cc4
Vardy, Mark E.
8dd019dc-e57d-4b49-8f23-0fa6d246e69d
Henstock, Timothy J.
27c450a4-3e6b-41f8-97f9-4e0e181400bb

Provenzano, Giuseppe, Vardy, Mark E. and Henstock, Timothy J. (2018) Decimetric-resolution stochastic inversion of shallow marine seismic reflection data; dedicated strategy and application to a geohazard case study. Geophysical Journal International, 214 (3), 1683-1700. (doi:10.1093/gji/ggy221).

Record type: Article

Abstract

Characterisation of the top 10-50 m of the subseabed is key for landslide hazard assessment, offshore structure engineering design and underground gas-storage monitoring. In this paper, we present a methodology for the stochastic inversion of ultra-high-frequency (UHF, 0.2-4.0 kHz) pre-stack seismic reflection waveforms, designed to obtain a decimetric-resolution re- mote elastic characterisation of the shallow sediments with minimal pre-processing and lit- tle a-priori information. We use a genetic algorithm in which the space of possible solutions is sampled by explicitly decoupling the short and long wavelengths of the P-wave velocity model. This approach, combined with an objective function robust to cycle skipping, outperforms a conventional model parametrisation when the ground-truth is offset from the centre of the search domain. The robust P-wave velocity model is used to precondition the width of the search range of the multi-parameter elastic inversion, thereby improving the efficiency in high dimensional parametrizations. Multiple independent runs provide a set of independent results from which the reproducibility of the solution can be estimated. In a real dataset acquired in Finneidfjord, Norway, we also demonstrate the sensitivity of UHF seismic inversion to shallow subseabed anomalies that play a role in submarine slope stability. Thus, the methodology has the potential to become an important practical tool for marine ground model building in spatially heterogeneous areas, reducing the reliance on expensive and time-consuming coring campaigns for geohazard mitigation in marine areas.

Text Provenzanoetal_Accepted18 - Accepted Manuscript
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More information

Accepted/In Press date: 1 June 2018
e-pub ahead of print date: 2 June 2018
Published date: 1 September 2018

Identifiers

Local EPrints ID: 422308
URI: https://eprints.soton.ac.uk/id/eprint/422308
ISSN: 0956-540X
PURE UUID: a89603f1-0743-4d46-ac36-ae3cb7f0b2af
ORCID for Timothy J. Henstock: ORCID iD orcid.org/0000-0002-2132-2514

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Date deposited: 20 Jul 2018 16:31
Last modified: 21 Jul 2018 00:34

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