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Christian Berndt - One of the best experts on this subject based on the ideXlab platform.
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repeated slope failure linked to fluid migration the ana Submarine Landslide complex eivissa channel western mediterranean sea
Earth and Planetary Science Letters, 2012Co-Authors: Angelo Camerlenghi, Miquel Canals, Christian Berndt, S Costa, Martin SaundersAbstract:Submarine slope failures are a well-known geohazard. They are able to destroy seafloor installations along their path and by generating tsunamis they may threaten coastal infrastructures. While the mechanisms involved in Submarine Landslide generation remain poorly known, there are observations that slope stability can be reduced in the presence of free gas. Here, we present new high-resolution 3D seismic data from the Eivissa Channel between the Iberian Penninsula and the Balearic Promontory in the Western Mediterranean Sea. The data reveal slope stability reduction in this area at least since mid-Quaternary times, and an intimate relationship between fluid migration and slope stability. We show that two Landslides, i.e. pre-Ana Slide and Ana Slide, occurred at almost the same location above an erosional channel in the Messinian unconformity. There is seismic evidence that fluids including gas are migrating upwards through this erosional surface and that they charge sedimentary layers at the base of the Ana Slide possibly reducing its strength and predisposing it to failure. Our data show in unprecedented detail the ways in which the presence of gas influences slope stability. The findings illustrate the importance of including high-resolution 3D seismic data in slope stability and tsunami risk assessments to identify shallow gas distribution as one of the main controls on slope stability in gas prone areas.
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tsunami modeling of a Submarine Landslide in the fram strait
Geochemistry Geophysics Geosystems, 2009Co-Authors: Christian Berndt, Sascha Brune, E G Nisbet, Jochen Zschau, S V SobolevAbstract:The present geological setting west of Svalbard closely parallels the situation off mid-Norway after the last glaciation, when crustal unloading by melting of ice induced very large earthquakes. Today, on the modern Svalbard margin, increasing bottom water temperatures are destabilizing marine gas hydrates, which are held in continental margin sediments consisting of interlayered contourite deposits and glacigenic debris flows. Both unloading earthquakes and hydrate failure have been identified as key factors causing several megaLandslides off Norway during early Holocene deglaciation. The most prominent event was the Storegga Slide 8200 years B.P. which caused a tsunami up to 23 m high on the Faroe and Shetland islands. Here we show by numerical tsunami modeling that a smaller Submarine Landslide west of Svalbard, 100 m high and 130 km wide, would cause a tsunami capable of reaching northwest Europe and threatening coastal areas. A tsunami warning system based on tiltmeters would give a warning time of 1–4 h.
Miquel Canals - One of the best experts on this subject based on the ideXlab platform.
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repeated slope failure linked to fluid migration the ana Submarine Landslide complex eivissa channel western mediterranean sea
Earth and Planetary Science Letters, 2012Co-Authors: Angelo Camerlenghi, Miquel Canals, Christian Berndt, S Costa, Martin SaundersAbstract:Submarine slope failures are a well-known geohazard. They are able to destroy seafloor installations along their path and by generating tsunamis they may threaten coastal infrastructures. While the mechanisms involved in Submarine Landslide generation remain poorly known, there are observations that slope stability can be reduced in the presence of free gas. Here, we present new high-resolution 3D seismic data from the Eivissa Channel between the Iberian Penninsula and the Balearic Promontory in the Western Mediterranean Sea. The data reveal slope stability reduction in this area at least since mid-Quaternary times, and an intimate relationship between fluid migration and slope stability. We show that two Landslides, i.e. pre-Ana Slide and Ana Slide, occurred at almost the same location above an erosional channel in the Messinian unconformity. There is seismic evidence that fluids including gas are migrating upwards through this erosional surface and that they charge sedimentary layers at the base of the Ana Slide possibly reducing its strength and predisposing it to failure. Our data show in unprecedented detail the ways in which the presence of gas influences slope stability. The findings illustrate the importance of including high-resolution 3D seismic data in slope stability and tsunami risk assessments to identify shallow gas distribution as one of the main controls on slope stability in gas prone areas.
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tracing seafloor methane emissions with benthic foraminifera results from the ana Submarine Landslide eivissa channel western mediterranean sea
Marine Geology, 2012Co-Authors: Giuliana Panieri, Angelo Camerlenghi, Isabel Cacho, Cristina Sanchez Cervera, Miquel Canals, Sara Lafuerza, Gemma HerreraAbstract:article The hypothesis that benthic foraminifera are useful proxies of local methane emissions from the seafloor has been verified on sediment core KS16 from the headwall of the Ana Submarine Landslide in the Eivissa Channel, Western Mediterranean Sea. The core MS312 from a nearby location with no known methane emis- sions is utilised as control. The core was analysed for biostratigraphy, benthic foraminiferal assemblages, Hyalinea balthica and Uvigerina peregrina carbon and oxygen stable isotope composition, and sedimentary structures. The upper part of the core records post-Landslide deglacial and Holocene normal marine hemipe- lagic sediments with highly abundant benthic foraminifera species that are typical of outer neritic to upper bathyal environment. In this interval, the δ 13 C composition of benthic foraminifera indicates normal marine environment analogous to those found in the control core. Below the sedimentary hiatus caused by the em- placement of the slide, the foraminiferal assemblages are characterised by lower density and higher Shannon Index. Markedly negative δ 13 C shifts in benthic foraminifera are attributed to the release of methane through the seabed. The mean values of the 13 C anomaly in U. peregrina are �0.951±0.208 in the pre-Landslide sediments, and �0.269±0.152 in post-slide reworked sediments deposited immediately above the hiatus. The δ 13
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the big 95 Submarine Landslide generated tsunami a numerical simulation
The Journal of Geology, 2012Co-Authors: Olaia Iglesias, Miquel Canals, Galderic Lastras, Maitane Olabarrieta, Mauricio Gonzalez, Inigo Anielquiroga, Luis Daniel Otero, Ruth Duran, David Amblas, J L CasamorAbstract:AbstractThis article presents a reasonable present-day, sea-level highstand numerical simulation and scenario for a potential tsunami generated by a Landslide with the characteristics of the BIG’95 debris flow, which occurred on the Ebro margin in the western Mediterranean Sea in prehistoric times (11,500 cal yr BP). The Submarine Landslide deposit covers an area of 2200 km2 of the slope and base of slope (200–1800-m water depth), involving a volume of 26 km3. A leapfrog finite difference model, COMCOT (Cornell multigrid coupled tsunami model), is used to simulate the propagation of the debris-flow-generated tsunami and its associated impact on the nearby Balearic Islands and Iberian coastlines. As a requisite of the model, reconstruction of the bathymetry before the Landslide occurrence and seafloor variation during landsliding have been developed based on the conceptual and numerical model of Lastras et al. (2005). We have also taken into account all available multibeam bathymetry of the area and high-r...
Angelo Camerlenghi - One of the best experts on this subject based on the ideXlab platform.
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repeated slope failure linked to fluid migration the ana Submarine Landslide complex eivissa channel western mediterranean sea
Earth and Planetary Science Letters, 2012Co-Authors: Angelo Camerlenghi, Miquel Canals, Christian Berndt, S Costa, Martin SaundersAbstract:Submarine slope failures are a well-known geohazard. They are able to destroy seafloor installations along their path and by generating tsunamis they may threaten coastal infrastructures. While the mechanisms involved in Submarine Landslide generation remain poorly known, there are observations that slope stability can be reduced in the presence of free gas. Here, we present new high-resolution 3D seismic data from the Eivissa Channel between the Iberian Penninsula and the Balearic Promontory in the Western Mediterranean Sea. The data reveal slope stability reduction in this area at least since mid-Quaternary times, and an intimate relationship between fluid migration and slope stability. We show that two Landslides, i.e. pre-Ana Slide and Ana Slide, occurred at almost the same location above an erosional channel in the Messinian unconformity. There is seismic evidence that fluids including gas are migrating upwards through this erosional surface and that they charge sedimentary layers at the base of the Ana Slide possibly reducing its strength and predisposing it to failure. Our data show in unprecedented detail the ways in which the presence of gas influences slope stability. The findings illustrate the importance of including high-resolution 3D seismic data in slope stability and tsunami risk assessments to identify shallow gas distribution as one of the main controls on slope stability in gas prone areas.
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tracing seafloor methane emissions with benthic foraminifera results from the ana Submarine Landslide eivissa channel western mediterranean sea
Marine Geology, 2012Co-Authors: Giuliana Panieri, Angelo Camerlenghi, Isabel Cacho, Cristina Sanchez Cervera, Miquel Canals, Sara Lafuerza, Gemma HerreraAbstract:article The hypothesis that benthic foraminifera are useful proxies of local methane emissions from the seafloor has been verified on sediment core KS16 from the headwall of the Ana Submarine Landslide in the Eivissa Channel, Western Mediterranean Sea. The core MS312 from a nearby location with no known methane emis- sions is utilised as control. The core was analysed for biostratigraphy, benthic foraminiferal assemblages, Hyalinea balthica and Uvigerina peregrina carbon and oxygen stable isotope composition, and sedimentary structures. The upper part of the core records post-Landslide deglacial and Holocene normal marine hemipe- lagic sediments with highly abundant benthic foraminifera species that are typical of outer neritic to upper bathyal environment. In this interval, the δ 13 C composition of benthic foraminifera indicates normal marine environment analogous to those found in the control core. Below the sedimentary hiatus caused by the em- placement of the slide, the foraminiferal assemblages are characterised by lower density and higher Shannon Index. Markedly negative δ 13 C shifts in benthic foraminifera are attributed to the release of methane through the seabed. The mean values of the 13 C anomaly in U. peregrina are �0.951±0.208 in the pre-Landslide sediments, and �0.269±0.152 in post-slide reworked sediments deposited immediately above the hiatus. The δ 13
Youkou Dong - One of the best experts on this subject based on the ideXlab platform.
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assessment of depth averaged method in analysing runout of Submarine Landslide
Landslides, 2020Co-Authors: Youkou Dong, Dong Wang, Lan CuiAbstract:Depth-averaged method (DAM) is one of the widely used numerical methods to back analyse the post-failure deposits of Submarine Landslides due to its high efficiency. However, its simplifications of the velocities along the thickness of the slide cannot capture complex behaviours such as shear band propagation. A novel non-averaged method, material point method (MPM), is used to validate the DAM analysis. The runout distances and morphologies of viscous debris flows predicted by the DAM and MPM are compared with those predicted by experiments and computational fluid dynamics analyses. The ranges of the shear strength, viscosity and sensitivity parameters are investigated to determine the feasibility of the DAM. The conventional DAM algorithm specialised for no-slip bases is enhanced to reproduce the phenomenon of block sliding of slides on frictional bases by considering the stability of the front and rear faces. Then, a spreading of horsts and grabens due to shear band propagation is presented with the MPM analysis. Two real cases of Submarine Landslides, Southern Mediterranean slide and Finneidfjord slide, were back-analysed with the DAM and MPM.
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correction to assessment of depth averaged method in analysing runout of Submarine Landslide
Landslides, 2020Co-Authors: Youkou Dong, Dong Wang, Lan CuiAbstract:The published version of this article, unfortunately, contained error. Figure 3 of “GPU-hosted workstation for parallel computing” was lost. Then the sequences of the Figures 4-10 were wrong. Given in this article are the correct figures.
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Runout of Submarine Landslide simulated with material point method
Journal of Hydrodynamics, 2017Co-Authors: Youkou Dong, Dong Wang, Mark F. RandolphAbstract:Most of the present knowledge on Submarine Landslides relies upon back-analysis of post-failure deposits identified using geophysical techniques. In this paper, the runout of slides on rigid bases is explored using the material point method (MPM) with focus on the geotechnical aspects of the morphologies. In MPM, the sliding material and bases are discretised into a number of Lagrangian particles, and a background Eulerian mesh is employed to update the state of the particles. The morphologies of the slide can be reproduced by tracking the Lagrangian particles in the dynamic processes. A real case history of a Submarine slide is back-analyzed with the MPM and also a depth-averaged method. Runout of the slides from steep slopes to moderate bases are reproduced. Then different combinations of soil and basal parameters are assumed to trigger runout mechanisms of elongation, block sliding and spreading. The runout distances predicted by the MPM match well with those from large deformation finite element analysis for the elongation and block sliding patterns. Horst and grabens are shaped in a spreading pattern. However, the current MPM simulations for materials with high sensitivities are relatively mesh sensitive.
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Investigation of impact forces on pipeline by Submarine Landslide using material point method
Ocean Engineering, 2017Co-Authors: Youkou Dong, Dong Wang, Mark F. RandolphAbstract:Quantitative assessment of impact forces by Submarine Landslide is significant for the safe operation of pipelines that must cross potential runout paths. In this paper, the transient process of a Submarine Landslide impacting a pipeline is modelled using the material point method (MPM) with an enhanced contact algorithm. For simplicity, the partially-embedded pipeline is assumed to be fixed in space. The Herschel-Bulkley rheological model is incorporated to reflect the dependence of the undrained shear strength of the sliding mass on the shear strain rate. The behaviour of the mass flowing over the pipe was reproduced by allowing separation between the pipe and the sliding mass. The horizontal impact forces predicted by the MPM are verified by comparison with those estimated using a computational fluid dynamics approach. The impact forces are interpreted with a hybrid model considering the combined effects due to the soil's inertia, its shear strength, and also the asymmetric static pressure of the sliding material. The coefficients for the three terms are retrieved by a best-fit to the results of an extensive parametric study. The effect of the projected height of the pipe above the seabed is also investigated.
Martin Saunders - One of the best experts on this subject based on the ideXlab platform.
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repeated slope failure linked to fluid migration the ana Submarine Landslide complex eivissa channel western mediterranean sea
Earth and Planetary Science Letters, 2012Co-Authors: Angelo Camerlenghi, Miquel Canals, Christian Berndt, S Costa, Martin SaundersAbstract:Submarine slope failures are a well-known geohazard. They are able to destroy seafloor installations along their path and by generating tsunamis they may threaten coastal infrastructures. While the mechanisms involved in Submarine Landslide generation remain poorly known, there are observations that slope stability can be reduced in the presence of free gas. Here, we present new high-resolution 3D seismic data from the Eivissa Channel between the Iberian Penninsula and the Balearic Promontory in the Western Mediterranean Sea. The data reveal slope stability reduction in this area at least since mid-Quaternary times, and an intimate relationship between fluid migration and slope stability. We show that two Landslides, i.e. pre-Ana Slide and Ana Slide, occurred at almost the same location above an erosional channel in the Messinian unconformity. There is seismic evidence that fluids including gas are migrating upwards through this erosional surface and that they charge sedimentary layers at the base of the Ana Slide possibly reducing its strength and predisposing it to failure. Our data show in unprecedented detail the ways in which the presence of gas influences slope stability. The findings illustrate the importance of including high-resolution 3D seismic data in slope stability and tsunami risk assessments to identify shallow gas distribution as one of the main controls on slope stability in gas prone areas.
