Integration of very-high-resolution seismic and CPTU data from a coastal area affected by shallow landsliding – the Finneidfjord natural laboratory

Vanneste, Maarten; Forsberg, Carl Fredrik; Knudsen, Siren; Kvalstad, Tore J.; L’Heureux, Jean-Sébastien; Lunne, Tom; Vardy, Mark E.; Chand, Shyam; Longva, Oddvar; Morgan, Eugene; Kopf, A.; Mörz, Tobias; Steiner, André; Brendryen, Jo; Haflidason, Haflidi

doi:10.1201/b18442-149

Cited by 5 publications

(3 citation statements)

References 4 publications

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“…Steiner et al 2012) identifies a composite 50-cm thick clay-rich bed with low stiffness, low density and high overpressure ratio that lies at shallow depth within the background silty-clay sediments (Vanneste et al 2012;Vardy et al 2012;Vardy 2015). This layer has been recognized as the failure plane for multiple submarine landslides from the last few decades and is thus referred to as event bed (L'Heureux et al 2012;Steiner et al 2012;Vanneste et al 2012Vanneste et al , 2015Vardy et al 2012). The saturation state of the event bed changes across the basin, from a water-saturated zone in the north to a gas-bearing area to the south (Vardy et al 2012;Morgan et al 2014).…”

Section: Acquisition Design and Background Informationmentioning

confidence: 99%

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

Provenzano

Vardy

Henstock

2018

Geophysical Journal International

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Characterization 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 remote elastic characterization of the shallow sediments with minimal pre-processing and little 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 parametrization 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 multiparameter elastic inversion, thereby improving the efficiency in highdimensional parametrizations. Multiple independent runs provide a set of independent results from which the reproducibility of the solution can be estimated. In a real data set 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.

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Section: Acquisition Design and Background Informationmentioning

confidence: 99%

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

Provenzano

Vardy

Henstock

2018

Geophysical Journal International

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“…This deformation inherently alters the nature of the sampled material, introducing uncertainties on key mechanical parameters (e.g., porosity, pore pressure, and undrained shear strength) that are difficult to quantify. Where geophysical and geotechnical data have been integrated, the methods either are highly qualitative (e.g., Vanneste et al 2015) or suffer from large uncertainties due to imprecisely calibrated relationships between the geophysical and geotechnical parameters (e.g., Nauroy et al 1998).…”

Section: Geological/sedimentological Viewpointmentioning

confidence: 99%

“…Where geophysical and geotechnical data have been integrated, the methods either are highly qualitative (e.g., Vanneste et al . ) or suffer from large uncertainties due to imprecisely calibrated relationships between the geophysical and geotechnical parameters (e.g., Nauroy et al . ).…”

Section: Introductionmentioning

confidence: 99%

State‐of‐the‐art remote characterization of shallow marine sediments: the road to a fully integrated solution

Vardy

Vanneste

Henstock

et al. 2017

Near Surface Geophysics

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Current methods for characterizing near‐surface marine sediments rely on extensive coring/pene‐trometer testing and correlation to seismic facies. Little quantitative information is regularly derived from geophysical data beyond qualitative inferences of sediment characteristics based on seismic facies architecture. Even these fundamental seismostratigraphic interpretations can be difficult to correlate with lithostratigraphic data due to inaccuracies in the time‐to‐depth conversion of geophysical data and potential loss and/or compression of high‐porosity and under‐consolidated sea‐floor material during direct sampling. To complicate matters further, when quantitative information is derived from marine geophysical data, it often describes the sediments using terminology (e.g., acoustic impedance and seismic quality factor) that is impenetrable to geologists and engineers. In contrast, for hydrocarbon prospecting, reservoir characterization using quantitative inversion of geophysical data has developed enormously over the past 20 years or more. Impedance and amplitude‐versus‐angle inversion techniques are now commonplace, whereas computationally expensive waveform inversions are gaining traction, and there is a well‐developed interface between these geophysical and reservoir engineering fields via rock physics. In this paper, we collate and review the different published inversion methods for high‐resolution geophysical data. Using several case study examples spanning a broad range of depositional environments, we assess the current state of the art in remote characterization of shallow sediments from a multidisciplinary viewpoint, encompassing geophysical, geological, and geotechnical angles. By identifying the key parameters used to characterize the subsurface, a framework is developed whereby geological, geotechnical, and geophysical characterizations of the subsurface can be related in a less subjective manner. As part of this, we examine the sensitivity of commonly derived acoustic properties (e.g., acoustic impedance and seismic quality factor) to more fundamentally important soil properties (e.g., lithology, pore pressure, gas saturation, and undrained shear strength), thereby facilitating better integration between geological, geotechnical, and geophysical data for improved mapping of sediment properties. Ultimately, we present a number of ideas for future research activities in this field.

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Data-Driven Ground Models: The Road to Fully-Integrated Site Characterization and Design

Vanneste

Sauvin

Dujardin

et al. 2022

Lecture Notes in Civil Engineering

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Integration of very-high-resolution seismic and CPTU data from a coastal area affected by shallow landsliding – the Finneidfjord natural laboratory

Cited by 5 publications

References 4 publications

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

State‐of‐the‐art remote characterization of shallow marine sediments: the road to a fully integrated solution

Data-Driven Ground Models: The Road to Fully-Integrated Site Characterization and Design

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