The Experts below are selected from a list of 237 Experts worldwide ranked by ideXlab platform
Christian Berndt - One of the best experts on this subject based on the ideXlab platform.
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Combining 3D seismics, eyewitness accounts and numerical simulations to reconstruct the 1888 Ritter Island sector collapse and tsunami
International Journal of Earth Sciences, 2020Co-Authors: Jens Karstens, Karim Kelfoun, Sebastian F. L. Watt, Christian BerndtAbstract:The 1888 Ritter Island volcanic sector collapse triggered a regionally damaging tsunami. Historic eyewitness accounts allow the reconstruction of the arrival time, phase and height of the tsunami wave at multiple locations around the coast of New Guinea and New Britain. 3D seismic interpretations and sedimentological analyses indicate that the catastrophic collapse of Ritter Island was preceded by a phase of deep-seated gradual spreading within the volcanic edifice and accompanied by a submarine explosive eruption, as the volcanic conduit was cut beneath sea level. However, the potential impact of the deep-seated deformation and the explosive eruption on tsunami genesis is unclear. For the first time, it is possible to parameterise the different components of the Ritter Island collapse with 3D seismic data, and thereby test their relative contributions to the tsunami. The modelled tsunami arrival times and heights are in good agreement with the historic eyewitness accounts. Our simulations reveal that the tsunami was primarily controlled by the displacement of the water column by the collapsing cone at the subaerial-submarine boundary and that the submerged fraction of the Slide Mass and its mobility had only a minor effect on tsunami genesis. This indicates that the total Slide volume, when incorporating the deep-seated deforming Mass, is not directly scalable for the resulting tsunami height. Furthermore, the simulations show that the tsunamigenic impact of the explosive eruption energy during the Ritter Island collapse was only minor. However, this relationship may be different for other volcanogenic tsunami events with smaller Slide volumes or larger magnitude eruptions, and should not be neglected in tsunami simulations and hazard assessment.
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scale invariant characteristics of the storegga Slide and implications for large scale submarine Mass movements
Marine Geology, 2008Co-Authors: Aaron Micallef, Christian Berndt, D G Masson, Dorrik A V StowAbstract:Abstract This study documents the fractal characteristics of submarine Mass movement statistics and morphology within the Storegga Slide. Geomorphometric mapping is used to identify one hundred and fifteen Mass movements from within the Storegga Slide scar and to extract morphological information about their headwalls. Analyses of this morphological information reveal the occurrence of spatial scale invariance within the Storegga Slide. Non-cumulative frequency-area distribution of Mass movements within the Storegga Slide satisfies an inverse power law with an exponent of 1.52. The headwalls exhibit geometric similarity at a wide range of scales and the lengths of headwalls scale with Mass movement areas. Composite headwalls are self-similar. One of the explanations of the observed spatial scale invariance is that the Storegga Slide is a geomorphological system that may exhibit self-organized criticality. In such a system, the input of sediment is in the form of hemipelagic sedimentation and glacial sediment deposition, and the output is represented by Mass movements that are spatially scale invariant. In comparison to subaerial Mass movements, the aggregate behavior of the Storegga Slide Mass movements is more comparable to that of the theoretical ‘sandpile’ model. The origin of spatial scale invariance may also be linked to the retrogressive nature of the Storegga Slide. The geometric similarity in headwall morphology implies that the slope failure processes are active on a range of scales, and that modeling of slope failures and geohazard assessment can extrapolate the properties of small landSlides to those of larger landSlides, within the limits of power law behavior. The results also have implications for the morphological classification of submarine Mass movements, because headwall shape can be used as a proxy for the type of Mass movement, which can otherwise only be detected with very high resolution acoustic data that are not commonly available.
R. Besso - One of the best experts on this subject based on the ideXlab platform.
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Alpine deep-seated gravitational slope deformation and the Messinian Salinity Crisis
Landslides, 2021Co-Authors: Y. Drouillas, T. Lebourg, S. Zerathe, J. C. Hippolyte, R. Chochon, M. Vidal, R. BessoAbstract:The southern part of the French Alps is studied for years in mapping and understanding of large-scale gravitational deformations. The identification and the knowledge of large-scale slope deformation (deep-seated gravitational slope deformation or DSGSD and deep-seated landSlide or DSL) in the previous work of Jomard ( 2006 ) and Zerathe ( 2013 ) open a new vision of landSlide processes with the reinterpretation of their dynamics and the characterization of the time scales involved. We identify DSGSD (10.10^9 m^3) in the Var Valley associated with geological and geomorphological anomalies linked to the Messinian Salinity Crisis (MSC) and the alpine orogenesis. We use field observations, geological information (geological map, boreholes), and topographic analysis performed in a GIS environment in order to describe these anomalies. This old and partly eroded Slide Mass is associated with three typical DSGSD features: (1) a double-crested ridge, the Sinne Valley, (2) a large formation (2.7 × 10^8 m^3) of slope deposit dated from the Messinian (Carros breccia), and (3) the kilometric deviation (1 to 2 km) of the Var River. We relate all these anomalies to the MSC (5.97 to 5.46 Ma) and the incision of deep canyons during this period related to this major eustatic variation (≈ 1300 m). The incision of the canyon triggered the collapse process of the DSGSD of the Sinne Valley and so destabilized the entire Massif. At present, three DSLs resulting from the DSGSD deformation are still present in the area in a dormant state. Indeed, since the infilling of the Var Canyon during the Pliocene, the activity of the DSGSD has stopped.
Dorrik A V Stow - One of the best experts on this subject based on the ideXlab platform.
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scale invariant characteristics of the storegga Slide and implications for large scale submarine Mass movements
Marine Geology, 2008Co-Authors: Aaron Micallef, Christian Berndt, D G Masson, Dorrik A V StowAbstract:Abstract This study documents the fractal characteristics of submarine Mass movement statistics and morphology within the Storegga Slide. Geomorphometric mapping is used to identify one hundred and fifteen Mass movements from within the Storegga Slide scar and to extract morphological information about their headwalls. Analyses of this morphological information reveal the occurrence of spatial scale invariance within the Storegga Slide. Non-cumulative frequency-area distribution of Mass movements within the Storegga Slide satisfies an inverse power law with an exponent of 1.52. The headwalls exhibit geometric similarity at a wide range of scales and the lengths of headwalls scale with Mass movement areas. Composite headwalls are self-similar. One of the explanations of the observed spatial scale invariance is that the Storegga Slide is a geomorphological system that may exhibit self-organized criticality. In such a system, the input of sediment is in the form of hemipelagic sedimentation and glacial sediment deposition, and the output is represented by Mass movements that are spatially scale invariant. In comparison to subaerial Mass movements, the aggregate behavior of the Storegga Slide Mass movements is more comparable to that of the theoretical ‘sandpile’ model. The origin of spatial scale invariance may also be linked to the retrogressive nature of the Storegga Slide. The geometric similarity in headwall morphology implies that the slope failure processes are active on a range of scales, and that modeling of slope failures and geohazard assessment can extrapolate the properties of small landSlides to those of larger landSlides, within the limits of power law behavior. The results also have implications for the morphological classification of submarine Mass movements, because headwall shape can be used as a proxy for the type of Mass movement, which can otherwise only be detected with very high resolution acoustic data that are not commonly available.
Y. Drouillas - One of the best experts on this subject based on the ideXlab platform.
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Alpine deep-seated gravitational slope deformation and the Messinian Salinity Crisis
Landslides, 2021Co-Authors: Y. Drouillas, T. Lebourg, S. Zerathe, J. C. Hippolyte, R. Chochon, M. Vidal, R. BessoAbstract:The southern part of the French Alps is studied for years in mapping and understanding of large-scale gravitational deformations. The identification and the knowledge of large-scale slope deformation (deep-seated gravitational slope deformation or DSGSD and deep-seated landSlide or DSL) in the previous work of Jomard ( 2006 ) and Zerathe ( 2013 ) open a new vision of landSlide processes with the reinterpretation of their dynamics and the characterization of the time scales involved. We identify DSGSD (10.10^9 m^3) in the Var Valley associated with geological and geomorphological anomalies linked to the Messinian Salinity Crisis (MSC) and the alpine orogenesis. We use field observations, geological information (geological map, boreholes), and topographic analysis performed in a GIS environment in order to describe these anomalies. This old and partly eroded Slide Mass is associated with three typical DSGSD features: (1) a double-crested ridge, the Sinne Valley, (2) a large formation (2.7 × 10^8 m^3) of slope deposit dated from the Messinian (Carros breccia), and (3) the kilometric deviation (1 to 2 km) of the Var River. We relate all these anomalies to the MSC (5.97 to 5.46 Ma) and the incision of deep canyons during this period related to this major eustatic variation (≈ 1300 m). The incision of the canyon triggered the collapse process of the DSGSD of the Sinne Valley and so destabilized the entire Massif. At present, three DSLs resulting from the DSGSD deformation are still present in the area in a dormant state. Indeed, since the infilling of the Var Canyon during the Pliocene, the activity of the DSGSD has stopped.
Haflidi Haflidason - One of the best experts on this subject based on the ideXlab platform.
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origin of shallow submarine Mass movements and their glide planes sedimentological and geotechnical analyses from the continental slope off northern norway
Journal of Geophysical Research, 2014Co-Authors: Nicole J Baeten, Jan Sverre Laberg, Maarten Vanneste, Carl Fredrik Forsberg, Tore J Kvalstad, Matthias Forwick, Tore O Vorren, Haflidi HaflidasonAbstract:Submarine landSlides are often characterized by a basal surface of rupture parallel to the stratigraphy, in which downslope movement is initiated. However, little is known about the sedimentology and physical properties of the sediments within these surfaces. In this study, we present a multiproxy analysis of the sediments collected from a giant piston core penetrating a shallow submarine Mass transport deposit, in combination with high-resolution seismoacoustic data to identify and characterize the basal glide plane and the weaker sediments in which movement was initiated. The initial phase of instability consists of a single fracture that formed due to the downslope movement of a mostly intact slab of sediments. The 16 m long core, comprising mostly undisturbed Massive and laminated ice-rafted debris-rich clay penetrated this slab. The base of the slab is characterized by a high-amplitude semicontinuous reflection visible on the subbottom profiler data at about 12.5 m depth, interpreted to originate from the glide plane on top of a plumite deposit. This plumite has dilative behavior with pore pressure decrease with increasing shear strain and high undrained shear strength. Movement probably started within contouritic sediments immediately above the glide plane, characterized by higher sensitivities and higher water contents. The occurrence of the Mass movements documented in this study are likely affected by the presence of a submarine landSlide complex directly downslope. The Slide scar of this landSlide complex promoted retrogressive movement farther upslope and progressive spreading of strain softening along the Slide base and in the Slide Mass. Numerical models (infinite slope, BING, and retrogressive slope models) illustrate that the present-day continental slope is essentially stable and allow reconstruction of the failure processes when initiated by an external trigger.