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  • Springer International Publishing  (3)
  • AAAS (American Association for the Advancement of Science)  (2)
  • 1
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    Gravitational collapse of Mount Etna’s southeastern flank (2018)
    AAAS (American Association for the Advancement of Science)
    In:  Science Advances, 4 (10). eaat9700.
    Details
    Publication Date: 2021-03-19
    Description: The southeastern flank of Etna volcano slides into the Ionian Sea at rates of centimeters per year. The prevailing understanding is that pressurization of the magmatic system, and not gravitational forces, controls flank movement, although this has also been proposed. So far, it has not been possible to separate between these processes, because no data on offshore deformation were available until we conducted the first long-term seafloor displacement monitoring campaign from April 2016 until July 2017. Unprecedented seafloor geodetic data reveal a 〉4-cm slip along the offshore extension of a fault related to flank kinematics during one 8-day-long event in May 2017, while displacement on land peaked at ~4 cm at the coast. As deformation increases away from the magmatic system, the bulk of Mount Etna’s present continuous deformation must be driven by gravity while being further destabilized by magma dynamics. We cannot exclude flank movement to evolve into catastrophic collapse, implying that Etna’s flank movement poses a much greater hazard than previously thought. The hazard of flank collapse might be underestimated at other coastal and ocean island volcanoes, where the dynamics of submerged flanks are unknown.
    Type: Article , PeerReviewed
    Format: text
    Format: text
    DOI: 10.1126/sciadv.aat9700
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    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 2
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    Temporal Constraints on Hydrate-Controlled Methane Seepage off Svalbard (2014)
    AAAS (American Association for the Advancement of Science)
    In:  Science, 343 (6168). pp. 284-287.
    Details
    Publication Date: 2019-10-17
    Description: Methane hydrate is an icelike substance that is stable at high pressure and low temperature in continental margin sediments. Since the discovery of a large number of gas flares at the landward termination of the gas hydrate stability zone off Svalbard, there has been concern that warming bottom waters have started to dissociate large amounts of gas hydrate and that the resulting methane release may possibly accelerate global warming. Here, we can corroborate that hydrates play a role in the observed seepage of gas, but we present evidence that seepage off Svalbard has been ongoing for at least three thousand years and that seasonal fluctuations of 1-2°C in the bottom-water temperature cause periodic gas hydrate formation and dissociation, which focus seepage at the observed sites.
    Type: Article , PeerReviewed
    Format: text
    Format: audio
    Format: text
    DOI: 10.1126/science.1246298
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    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 3
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    Mass Wasting History within Lake Ohrid Basin (Albania/Macedonia) over the last 600 ka. (2016)
    Springer International Publishing
    In:  In: Submarine Mass Movements and their Consequences. Advances in Natural and Technological Hazards Research, 41 . Springer International Publishing, pp. 291-300. ISBN 978-3-319-20978-4
    Details
    Publication Date: 2019-09-23
    Description: Lake Ohrid (LO), a transboundary lake shared by Macedonia and Albania on the Balkan Peninsula, is not only considered to be the oldest lake in Europe (~2 Ma) but has a long and continuous sedimentary history. An advantage at LO is the availability of hydroacoustic data sets of good quality covering the entire lake basin. The tectonically formed basin is filled with thick undisturbed sediments. However, the overall internal structure of LO is characterized by numerous faults, clinoform structures, and several Mass Transport Deposits (MTDs). By using a seismic chronology model (SCM) correlating seismic reflector packages with Marine Isotope Stages (MIS) we estimate the occurrence of the deepest MTD detected in the southern basin at the transition of MIS9 to MIS8 (~300 ka) defining the onset of the sliding history in LO that is still ongoing today. In general, MTDs are widespread within the basin but they do cluster at active faults. Two large MTDs occurred in the early MIS7 (~230 ka, ~220 ka) and after a quiesence period of about ~70 ka two additional large MTDs have been detected in the late penultimate glacial period MIS6 (~150 ka, 130 ka). MIS5 seemed to be another quiet period with respect to mass wasting. In the younger sedimentary history mass movement is a common process with several large and mid-sized deposits mapped at all stratigraphic levels. The youngest slide deposits are estimated to occur within the last 2,000 years. The main outcome of this paper is a model for the spatial and temporal distribution of mass wasting for Lake Ohrid.
    Type: Book chapter , NonPeerReviewed
    DOI: 10.1007/978-3-319-20979-1_29
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    OceanRep: Book chapter
  • 4
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    Flow Behaviour of a Giant Landslide and Debris Flow Entering Agadir Canyon, NW Africa (2016)
    Springer International Publishing
    In:  In: Submarine Mass Movements and their Consequences : 7th International Symposium. , ed. by Lamarche, G. Springer International Publishing, Cham, pp. 145-154.
    Details
    Publication Date: 2017-11-22
    Description: Agadir Canyon is one of the largest submarine canyons in the World, supplying giant submarine sediment gravity flows to the Agadir Basin and the wider Moroccan Turbidite System. While the Moroccan Turbidite System is extremely well investigated, almost no data from the source region, i.e. the Agadir Canyon, are available. New acoustic and sedimentological data of the Agadir Canyon area were collected during RV Maria S. Merian Cruise 32 in autumn 2013. The data show a prominent headwall area around 200 km south of the head of Agadir Canyon. The failure occurred along a pronounced weak layer in a sediment wave field. The slab-type failure rapidly disintegrated and transformed into a debris flow, which entered Agadir Canyon at 2500 m water depth. Interestingly, the debris flow did not disintegrate into a turbidity current when it entered the canyon despite a significant increase in slope angle. Instead, the material was transported as debrite for at least another 200 km down the canyon. It is unlikely that this giant debris flow significantly contributed to the deposits in the wider Moroccan Turbidite System.
    Type: Book chapter , NonPeerReviewed
    DOI: 10.1007/978-3-319-20979-1_14
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    OceanRep: Book chapter
  • 5
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    Shallow Gas and the Development of a Weak Layer in Submarine Spreading, Hikurangi Margin (New Zealand) (2016)
    Springer International Publishing
    In:  In: Submarine Mass Movements and Their Consequences : 7th International Symposium. , ed. by Lamarche, G., Mountjoy, J., Bull, S. and Hubble, T. Advances in Natural and Technological Hazards Research, 37 . Springer International Publishing, Cham, pp. 419-426. ISBN 9783319209784
    Details
    Publication Date: 2021-05-11
    Description: Submarine spreading is a type of mass movement that involves the extension and fracturing of a thin surficial layer of sediment into coherent blocks and their finite displacement on a gently sloping slip surface. Its characteristic seafloor signature is a repetitive pattern of parallel ridges and troughs oriented perpendicular to the direction of mass movement. We map ~30 km2 of submarine spreads on the upper slope of the Hikurangi margin, east of Poverty Bay, North Island, New Zealand, using multibeam echosounder and 2D multichannel seismic data. These data show that spreading occurs in thin, gently-dipping, parallel-bedded clay, silt and sandy sedimentary units deposited as lowstand clinoforms. More importantly, high-amplitude and reverse polarity seismic reflectors, which we interpret as evidence of shallow gas accumulations, occur extensively in the fine sediments of the upper continental slope, but are either significantly weaker or entirely absent where the spreads are located. We use this evidence to propose that shallow gas, through the generation of pore pressure, has played a key role in establishing the failure surface above which submarine spreading occurred. Additional dynamic changes in pore pressure could have been triggered by a drop in sea level during the Last Glacial Maximum and seismic loading.
    Type: Book chapter , NonPeerReviewed
    DOI: 10.1007/978-3-319-20979-1_42
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    OceanRep: Book chapter
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