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  • PANGAEA  (366)
  • Elsevier  (3)
  • European Marine Board  (1)
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  • 1
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    Heat flow anomalies in the Gulf of Cadiz and off Cape San Vincente, Portugal (2009)
    Elsevier
    In:  Marine and Petroleum Geology, 26 . pp. 795-804.
    Details
    Publication Date: 2017-09-13
    Description: Heat flow anomalies provide critical information in active tectonic environments. The Gulf of Cadiz and adjacent areas are affected by the plate convergence between Africa and Europe, causing widespread deformation and faulting. Active thrust faults cause lateral movement and advection of heat that produces systematic variations in surface heat flow. In December 2003 new heat flow data were collected during the research vessel Sonne cruise SO175 in the Gulf of Cadiz over two sites of recent focused research activity: (i) the Gulf of Cadiz sedimentary prism and (ii) the Marques de Pombal escarpment. Both features have also been discussed as potential source areas of the Great Lisbon earthquake and tsunami of 1755. Background heat flow at the eastern terminus of the Horseshoe abyssal plain is about 52–59 mW/m2. Over the Gulf of Cadiz prism, heat flow decreases from ∼57 mW/m2 to unusually low values of 45 mW/m2 roughly 120 km eastward. Such low values and the heat flow trend are typical for active thrusting, supporting the idea of an east-dipping thrust fault. Slip rates are 10 ± 5 mm per year, assuming that the fault dips at 2°. A fault dipping at 5°, however, would result into slip rates of 1.5–5 mm per year, suggesting that subduction has largely ceased. Based on seismic data, the Marques de Pombal fault is interpreted as part of an active fault system located ∼100 km westward of Cape San Vincente. Heat flow over the fault is affected by refraction of heat caused by the 1 km high escarpment. Thermal models suggest that the slip rate along the fault must either be small or shear stresses acting on the fault are rather high. With respect to other fault zones, however, it is reasonable to assume that the fault's slip rate is small.
    Type: Article , PeerReviewed
    Format: text
    DOI: 10.1016/j.marpetgeo.2008.08.006
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    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 2
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    A new evidence for mass wasting at the NE Cretan slope: a multi-stage slide complex from the eastern Mediterranean (2009)
    Elsevier
    In:  Marine Geology, 263 . pp. 97-107.
    Details
    Publication Date: 2017-08-04
    Description: Newly acquired bathymetric and seismic reflection data have revealed mass-transport deposits (MTDs) on the northeastern Cretan margin in the active Hellenic subduction zone. These include a stack of two submarine landslides within the Malia Basin with a total volume of approximately 4.6 km(3) covering an area of about 135 km(2). These two MTDs have different geometry, internal deformations and transport structures. The older and stratigraphic lower MTD is interpreted as a debrite that fills a large part of the Malia Basin, while the second, younger MTD, with an age of at least 12.6 cal. ka B.P., indicate a thick, lens-shaped, partially translational landslide. This MTD comprises multiple slide masses with internal structure varying from highly deformed to nearly undeformed. The reconstructed source area of the older MTD is located in the westernmost Malia Basin. The source area of the younger MTD is identified in multiple headwalls at the slope-basin-transition in 450 m water depth. Numerous faults with an orientation almost parallel to the southwest-northeast-trending basin axis occur along the northern and southern boundaries of the Malia Basin and have caused a partial steepening of the slope-basin-transition. The possible triggers for slope failure and mass-wasting include (i) seismicity and (ii) movement of the uplifting island of Crete from neotectonics of the Hellenic subduction zone, and (iii) slip of clay-mineral-rich or ash-bearing layers during fluid involvement. (c) 2009 Elsevier B.V. All rights reserved.
    Type: Article , PeerReviewed
    Format: text
    DOI: 10.1016/j.margeo.2009.04.002
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    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 3
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    Cone penetration testing to assess slope stability in the 1979 Nice landslide area (Ligurian Margin, SE France) (2015)
    Elsevier
    In:  Marine Geology, 369 . pp. 162-181.
    Details
    Publication Date: 2015-09-24
    Description: Highlights: • Comprehensive morphological, seismic, sedimentological, and geotechnical data sets. • Dynamic CPTU provides a powerful, time- and cost-efficient in situ technique. • Development of a regional sub-seafloor strength model offshore Nice airport. • 2D finite element slope stability assessment gives slope failure depth of 〉 50 m. Abstract: In the landslide-prone area near the Nice international airport, southeastern France, an interdisciplinary approach is applied to develop realistic lithological/geometrical profiles and geotechnical/strength sub-seafloor models. Such models are indispensable for slope stability assessments using limit equilibrium or finite element methods. Regression analyses, based on the undrained shear strength (su) of intact gassy sediments are used to generate a sub-seafloor strength model based on 37 short dynamic and eight long static piezocone penetration tests, and laboratory experiments on one Calypso piston and 10 gravity cores. Significant strength variations were detected when comparing measurements from the shelf and the shelf break, with a significant drop in su to 5.5 kPa being interpreted as a weak zone at a depth between 6.5 and 8.5 m below seafloor (mbsf). Here, a 10% reduction of the in situ total unit weight compared to the surrounding sediments is found to coincide with coarse-grained layers that turn into a weak zone and detachment plane for former and present-day gravitational, retrogressive slide events, as seen in 2D chirp profiles. The combination of high-resolution chirp profiles and comprehensive geotechnical information allows us to compute enhanced 2D finite element slope stability analysis with undrained sediment response compared to previous 2D numerical and 3D limit equilibrium assessments. Those models suggest that significant portions (detachment planes at 20 m or even 55 mbsf) of the Quaternary delta and slope apron deposits may be mobilized. Given that factors of safety are equal or less than 1 when further considering the effect of free gas, a high risk for a landslide event of considerable size off Nice international airport is identified.
    Type: Article , PeerReviewed
    Format: text
    DOI: 10.1016/j.margeo.2015.08.008
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    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 4
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    Marine Geohazards: Safeguarding society and the Blue Economy from a hidden threat (2023)
    European Marine Board | Ostend, Belgium
    Details
    Publication Date: 2023-12-20
    Description: Marine geohazards pose a significant threat to the European coastal population and to the development of the Blue Economy. This Position Paper discusses the type, distribution and impact of marine geohazards on the European coastal regions and the Blue Economy, as well as what and how novel scientific approaches may broaden our understanding of their trigger mechanisms and drive a risk-mitigating European policy.
    Description: Challenge 6: Increase community resilience to ocean hazards; Challenge 7: Expand the Global Ocean Observing System.
    Description: Published
    Description: Refereed
    Keywords: Blue Economy ; Marine geohazards ; Coastal region
    Repository Name: AquaDocs
    Type: Book/Monograph/Conference Proceedings
    Format: 100pp
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    PAPER (OA)
  • 5
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    (Appendix 1) Pore water analysis from sediment cores in the area of a landslide scar close to the airport of Nice (2017)
    PANGAEA
    Details
    Publication Date: 2023-03-14
    Keywords: Alkalinity, total; Aluminium; Ammonium; Barium; Boron; Bromide; Calcium; Chloride; Conductivity; Copper; DEPTH, sediment/rock; Event label; GC; GeoB13918; GeoB13919; GeoB13925; GeoB13926; GeoB13928; GeoB13929; GeoB13930; GeoB13934; GeoB13939; GeoB13940; GeoB13946; GeoB13952; GeoB13953; Gravity corer; Iron; Leibniz Centre for Tropical Marine Research; Lithium; Magnesium; Manganese; Oxidation reduction (RedOx) potential; pH; Phosphorus; POS386; Poseidon; Potassium; Silicon; Sodium; Strontium; Sulfate; Sulfur; Zinc; ZMT; δ18O; δ18O, standard deviation; δ Deuterium; δ Deuterium, standard deviation
    Type: Dataset
    Format: text/tab-separated-values, 5330 data points
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    DATA PANGAEA
  • 6
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    Grain-size distribution of sediment cores from the Nice Slope (2015)
    PANGAEA
    Details
    Publication Date: 2023-03-09
    Keywords: Center for Marine Environmental Sciences; Comment; Density, dry bulk; DEPTH, sediment/rock; Elevation of event; Event label; GC; GeoB13919; GeoB13928; GeoB13929; GeoB13936; GeoB13941; GeoB13946; GeoB13952; GeoB16542-1; Gravity corer; Latitude of event; Lithology/composition/facies; Location; Longitude of event; MARUM; Nice Slope; POS386; POS429; POS429_085-1; Poseidon; Sand; Size fraction 〈 0.002 mm, clay; Size fraction 〉 0.006 mm, silt; Size fraction 0.125-0.063 mm, 3.0-4.0 phi, very fine sand; Size fraction 0.250-0.125 mm, 2.0-3.0 phi, fine sand; Size fraction 0.500-0.250 mm, 1.0-2.0 phi, medium sand; Size fraction 2.000-0.630 mm, coarse sand; Size fraction 2.000-1.000 mm, (-1.0)-0.0 phi, very coarse sand; Vertical stress
    Type: Dataset
    Format: text/tab-separated-values, 119 data points
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    DATA PANGAEA
  • 7
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    (Figure 2) Suspended sediment concentration profiles from water samples in the outer harbor of Emden, Germany (2012)
    PANGAEA
    Details
    Publication Date: 2023-03-03
    Keywords: Center for Marine Environmental Sciences; DEPTH, water; Emden_Harbour_WS1250; Emden Harbour, Germany; MARUM; Suspended particulate matter; Water sample; Weighing dry mass per unit sample volume; WS; WS1250
    Type: Dataset
    Format: text/tab-separated-values, 6 data points
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    DATA PANGAEA
  • 8
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    Hydrocarbon analyses of submarine mud volcanoes (MV) in the Kumano forearc basin (2014)
    PANGAEA
    In:  Supplement to: Pape, Thomas; Geprägs, Patrizia; Hammerschmidt, Sebastian; Wintersteller, Paul; Wei, Jiangong; Fleischmann, Timo; Bohrmann, Gerhard; Kopf, Achim J (2014): Hydrocarbon seepage and its sources at mud volcanoes of the Kumano forearc basin, Nankai Trough subduction zone. Geochemistry, Geophysics, Geosystems, 15(6), 2180-2194, https://doi.org/10.1002/2013GC005057
    Details
    Publication Date: 2023-03-03
    Description: Twelve submarine mud volcanoes (MV) in the Kumano forearc basin within the Nankai Trough subduction zone were investigated for hydrocarbon origins and fluid dynamics. Gas hydrates diagnostic for methane concentrations exceeding solubilities were recovered from MVs 2, 4, 5, and 10. Molecular ratios (C1/C2〈250) and stable carbon isotopic compositions (d13C-CH4 〉-40 per mil V-PDB) indicate that hydrate-bound hydrocarbons (HCs) at MVs 2, 4, and 10 are derived from thermal cracking of organic matter. Considering thermal gradients at the nearby IODP Sites C0009 and C0002, the likely formation depth of such HCs ranges between 2300 and 4300 m below seafloor (mbsf). With respect to basin sediment thickness and the minimum distance to the top of the plate boundary thrust we propose that the majority of HCs fueling the MVs is derived from sediments of the Cretaceous to Tertiary Shimanto belt below Pliocene/Pleistocene to recent basin sediments. Considering their sizes and appearances hydrates are suggested to be relicts of higher MV activity in the past, although the sporadic presence of vesicomyid clams at MV 2 showed that fluid migration is sufficient to nourish chemosynthesis-based organisms in places. Distributions of dissolved methane at MVs 3, 4, 5, and 8 pointed at fluid supply through one or few MV conduits and effective methane oxidation in the immediate subsurface. The aged nature of the hydrates suggests that the major portion of methane immediately below the top of the methane-containing sediment interval is fueled by current hydrate dissolution rather than active migration from greater depth.
    Keywords: Center for Marine Environmental Sciences; MARUM
    Type: Dataset
    Format: application/zip, 31 datasets
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    DATA PANGAEA
  • 9
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    Slope stability analyses based on sediment cores of the Ligurian Margin, Southern France (2014)
    PANGAEA
    In:  Supplement to: Ai, Fei; Förster, Annika; Stegmann, Sylvia; Kopf, Achim J (2014): Geotechnical Characteristics and Slope Stability Analysis on the Deeper Slope of the Ligurian Margin, Southern France. In: Kyoji Sassa, Paolo Canuti, Yueping Yin (eds.), Landslide Science for a Safer Geoenvironment, Volume 3: Targeted Landslides. Springer International Publishing AG, Switzerland, 549-555, https://doi.org/10.1007/978-3-319-04996-0_84
    Details
    Publication Date: 2023-03-03
    Description: Submarine slope failures of various types and sizes are common along the tectonic and seismically active Ligurian margin, northwestern Mediterranean Sea, primarily because of seismicity up to ~M6, rapid sediment deposition in the Var fluvial system, and steepness of the continental slope (average 11°). We present geophysical, sedimentological and geotechnical results of two distinct slides in water depth 〉1,500 m: one located on the flank of the Upper Var Valley called Western Slide (WS), another located at the base of continental slope called Eastern Slide (ES). WS is a superficial slide characterized by a slope angle of ~4.6° and shallow scar (~30 m) whereas ES is a deep-seated slide with a lower slope angle (~3°) and deep scar (~100 m). Both areas mainly comprise clayey silt with intermediate plasticity, low water content (30-75 %) and underconsolidation to strong overconsolidation. Upslope undeformed sediments have low undrained shear strength (0-20 kPa) increasing gradually with depth, whereas an abrupt increase in strength up to 200 kPa occurs at a depth of ~3.6 m in the headwall of WS and ~1.0 m in the headwall of ES. These boundaries are interpreted as earlier failure planes that have been covered by hemipelagite or talus from upslope after landslide emplacement. Infinite slope stability analyses indicate both sites are stable under static conditions; however, slope failure may occur in undrained earthquake condition. Peak earthquake acceleration from 0.09 g on WS and 0.12 g on ES, i.e. M5-5.3 earthquakes on the spot, would be required to induce slope instability. Different failure styles include rapid sedimentation on steep canyon flanks with undercutting causing superficial slides in the west and an earthquake on the adjacent Marcel fault to trigger a deep-seated slide in the east.
    Keywords: Center for Marine Environmental Sciences; MARUM
    Type: Dataset
    Format: application/zip, 20 datasets
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    DATA PANGAEA
  • 10
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    Grain-size distribution and frictional behaviour of sediment cores from the Nice Slope (2015)
    PANGAEA
    In:  Supplement to: Stegmann, Sylvia; Kopf, Achim J (2014): How stable is the Nice slope? An analysis based on strength and cohesion from ring shear experiments. In: Krastel S et al. (eds.) Submarine Mass Movements and Their Consequences. Springer, Heidelberg, 189-200, https://doi.org/10.1007/978-3-319-00972-8_17
    Details
    Publication Date: 2023-03-03
    Description: The upper shelf of the landslide-prone Ligurian Margin (Western Mediterranean Sea) off Nice well-known for the 1979 Airport Landslide is a natural laboratory to study preconditioning factors and trigger mechanisms for submarine landslides. For this study low-stress ring shear experiments have been carried out on a variety of sediments from 〉50 gravity cores to characterise the velocity-dependent frictional behaviour. Mean values of the peak coefficient of friction vary from 0.46 for clay-dominated samples (53 % clay, 46 % silt, 1 %) sand up to 0.76 for coarse-grained sediments (26 % clay, 57 % silt, 17 % sand). The majority of the sediments tested show velocity strengthening regardless of the grain size distribution. For clayey sediments the peak and residual cohesive strength increases with increasing normal stress, with values from 1.3 to 10.6 kPa and up to 25 % of all strength supported by cohesive forces in the shallowmost samples. A pseudo-static slope stability analysis reveals that the different lithologies (even clay-rich material with clay content 〉=50 %) tested are stable up to slope angles 〈26° under quasi-drained conditions.
    Keywords: Center for Marine Environmental Sciences; MARUM
    Type: Dataset
    Format: application/zip, 2 datasets
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    DATA PANGAEA
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