scholarly journals Are submarine landslides an underestimated hazard on the western North Atlantic passive margin?

Geology ◽  
2019 ◽  
Vol 47 (9) ◽  
pp. 848-852 ◽  
Author(s):  
Alexandre Normandeau ◽  
D. Calvin Campbell ◽  
David J.W. Piper ◽  
Kimberley A. Jenner
Keyword(s):  
North Atlantic ◽  
Late Holocene ◽  
Detailed Examination ◽  
Submarine Landslide ◽  
Passive Margin ◽  
Submarine Landslides ◽  
Eastern Canada ◽  
Grand Banks ◽  
Landslide Event ◽  
Slope Instabilities

AbstractThe western North Atlantic passive margin is considered relatively stable, with few slope instabilities recognized during the Holocene. However, new multibeam bathymetry mapping and sediment core acquisition off eastern Canada indicate that previously unidentified, large, submarine landslide events occurred during the Late Holocene, between 4 and 1.5 ka. The recognition of these new gravitational events, in addition to the well-known C.E. 1929 Grand Banks earthquake-induced landslide, indicates that approximately one large landslide event per 1000 years has occurred offshore eastern Canada within the past 4000 years, a much shorter recurrence interval than hitherto reported. This Late Holocene recurrence rate is also similar to active margins around the world and is likely due to the under-consolidation and resultant instability of Scotian Slope sediments attributable to high glacial sedimentation rates. The discovery of these new Late Holocene landslides was made possible through detailed examination of cores recovered from the lower slope. These results demonstrate that submarine landslide hazard has been underestimated on the western North Atlantic margin—home to significant submarine infrastructure and proximal to a large coastal population.

Submarine Landslides and Their Tsunami Hazard

2016 ◽  
Vol 49 (1) ◽  
Author(s):  
David R. Tappin
Keyword(s):  
Papua New Guinea ◽  
New Guinea ◽  
Submarine Landslide ◽  
Tsunami Hazard ◽  
Publication Date ◽  
Submarine Landslides ◽  
Critical Importance ◽  
Grand Banks ◽  
Landslide Mechanisms ◽  
Landslide Tsunamis

Most tsunamis are generated by earthquakes, but in 1998, a seabed slump offshore of northern Papua New Guinea (PNG) generated a tsunami up to 15 m high that killed more than 2,200 people. The event changed our understanding of tsunami mechanisms and was forerunner to two decades of major tsunamis that included those in Turkey, the Indian Ocean, Japan, and Sulawesi and Anak Krakatau in Indonesia. PNG provided a context to better understand these tsunamis as well as older submarine landslide events, such as Storegga (8150 BP); Alika 2 in Hawaii (120,000 BP), and Grand Banks, Canada (1929), together with those from dual earthquake/landslide mechanisms, such as Messina (1908), Puerto Rico (1928), and Japan (2011). PNG proved that submarine landslides generate devastating tsunamis from failure mechanisms that can be very different, whether singly or in combination with earthquakes. It demonstrated the critical importance of seabed mapping to identify these mechanisms as well as stimulated the development of new numerical tsunami modeling methodologies. In combination with other recent tsunamis, PNG demonstrated the critical importance of these events in advancing our understanding of tsunami hazard and risk. This review recounts how, since 1998, understanding of the tsunami hazard from submarine landslides has progressed far beyond anything considered possible at that time. ▪ For submarine landslide tsunamis, advances in understanding take place incrementally, usually in response to major, sometimes catastrophic, events. ▪ The Papua New Guinea tsunami in 1998, when more than 2,200 people perished, was a turning point in first recognizing the significant tsunami hazard from submarine landslides. ▪ Over the past 2 to 3 years advances have also been made mainly because of improvements in numerical modeling based on older tsunamis such as Grand Banks in 1929, Messina in 1908, and Storegga at 8150 BP. ▪ Two recent tsunamis in late 2018, in Sulawesi and Anak Krakatau, Indonesia, where several hundred people died, were from very unusual landslide mechanisms—dual (strike-slip and landslide) and volcanic collapse—and provide new motivations for understanding these tsunami mechanisms. ▪ This is a timely, state of the art review of landslide tsunamis based on recent well-studied events and new research on older ones, which provide an important context for the recent tsunamis in Indonesia in 2018. Expected final online publication date for the Annual Review of Earth and Planetary Sciences, Volume 49 is May 2021. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

Submarine landslide catalogue onshore/offshore harmonization: Spain as a case study

2018 ◽  
Vol 477 (1) ◽  
pp. 497-510 ◽  
Author(s):  
Ricardo León ◽  
Juan Carlos García-Davalillo ◽  
David Casas ◽  
Carmen Julia Giménez-Moreno
Keyword(s):  
Spatial Information ◽  
Submarine Landslide ◽  
Submarine Landslides ◽  
Data Types ◽  
Landslide Event ◽  
Data Source ◽  
Geological Timescale ◽  
Different Sources

AbstractThis paper presents a Geographic Information System catalogue of the submarine landslides of the Spanish continental margin and describes the problems associated with harmonizing the catalogue with its onshore homologue. The data model structure is described to explain how to apply the rules and specifications following the Infrastructure for Spatial Information in Europe (INSPIRE). Because of the singularities of the marine environment compared with those of land, integrating the submarine landslide catalogues into INSPIRE specifications requires the following procedures: (1) simplification of the list of values of state of activity into three categories: active, dormant and relict; and (2) inclusion of debris avalanches and turbidites as new typologies of landslides. This paper discusses the problems associated with harmonizing different data types and units from different sources, such as the thickness (metres and seismic two travel time) or the age of the event, and a numeric code for the geological timescale is proposed to harmonize these data. We establish whether an item is required based on the reliability of the landslide event, which is categorized by three levels (high–middle–low) depending on the precision of the data source, methodology used and quality of the publication where the data are obtained.

Tectonic and geomorphic controls on the distribution of submarine landslides across active and passive margins, eastern New Zealand

2019 ◽  
Vol 500 (1) ◽  
pp. 477-494 ◽  
Author(s):  
S. J. Watson ◽  
J. J. Mountjoy ◽  
G. J. Crutchley
Keyword(s):  
New Zealand ◽  
Slope Failure ◽  
Submarine Landslide ◽  
Passive Margin ◽  
Continental Margins ◽  
Submarine Landslides ◽  
Mass Wasting ◽  
Active Margin ◽  
Passive Margins ◽  
Marine Habitats

AbstractSubmarine landslides occur on continental margins globally and can have devastating consequences for marine habitats, offshore infrastructure and coastal communities due to potential tsunamigenesis. Therefore, understanding landslide magnitude and distribution is central to marine and coastal hazard planning.We present the first submarine landslide database for the eastern margin of New Zealand comprising >2200 landslides occurring in water depths from c. 300–4000 m. Landslides are more prevalent and, on average, larger on the active margin compared with the passive margin. We attribute higher concentrations of landslides on the active margin to tectonic processes including uplift and oversteepening, faulting and seamount subduction. Submarine landslide scars are concentrated around canyon systems and close to canyon thalwegs. This suggests that not only does mass wasting play a major role in canyon evolution, but also that canyon-forming processes may provide preconditioning factors for slope failure.Results of this study offer unique insights into the spatial distribution, magnitude and morphology of submarine landslides across different geological settings, providing a better understanding of the causative factors for mass wasting in New Zealand and around the world.

scholarly journals Evidence of Lithospheric Boudinage in the Grand Banks of Newfoundland from Geophysical Observations

Geosciences ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 55
Author(s):  
Malcolm D. J. MacDougall ◽  
Alexander Braun ◽  
Georgia Fotopoulos
Keyword(s):  
Passive Margin ◽  
Eastern Canada ◽  
Grand Banks ◽  
Long Wavelength ◽  
Passive Margins ◽  
Multi Stage ◽  
Crustal Thinning ◽  
Gravity And Magnetic ◽  
Magnetic Signatures ◽  
Seismic Sections

The evolution of the passive margin off the coast of Eastern Canada has been characterized by a series of rifting episodes which caused widespread extension of the lithosphere and associated structural anomalies, some with the potential to be classified as a result of lithospheric boudinage. Crustal thinning of competent layers is often apparent in seismic sections, and deeper Moho undulations may appear as repeating elongated anomalies in gravity and magnetic surveys. By comparing the similar evolutions of the Grand Banks and the Norwegian Lofoten-Vesterålen passive margins, it is reasonable to explore the potential of the same structures being present. This investigation supplements our knowledge of analogous examples in the Norwegian Margin and the South China Sea with a thorough investigation of seismic, gravity and magnetic signatures, to determine that boudinage structures are evident in the context of the Grand Banks. Through analysis of geophysical data (including seismic, gravity and magnetic observations), a multi-stage boudinage mechanism is proposed, which is characterized by an upper crust short-wavelength deformation ranging from approximately 20–80 km and a lower crust long-wavelength deformation exceeding 200 km in length. In addition, the boudinage mechanism caused slightly different structures which are apparent in the block geometry and layeredness. Based on these results, there are indications that boudinage wavelength increases with each successive rifting phase, with geometry changing from domino style to a more shearband/symmetrical style as the scale of deformation is increased to include the entire lithosphere.

scholarly journals North Atlantic marine 14C reservoir effects: Implications for late-Holocene chronological studies

2009 ◽  
Vol 4 (3) ◽  
pp. 171-180 ◽  
Author(s):  
P.L. Ascough ◽  
G.T. Cook ◽  
A.J. Dugmore
Keyword(s):  
North Atlantic ◽  
Late Holocene

Simulation of tsunami waves generated by submarine landslides in the Black Sea

2015 ◽  
Vol 30 (4) ◽  
Author(s):  
Gayaz S. Khakimzyanov ◽  
Oleg I. Gusev ◽  
Sofya A. Beizel ◽  
Leonid B. Chubarov ◽  
Nina Yu. Shokina
Keyword(s):  
Surface Waves ◽  
Black Sea ◽  
Numerical Technique ◽  
Submarine Landslide ◽  
The Black Sea ◽  
Submarine Landslides ◽  
Hydrodynamic Approximation ◽  
Tsunami Waves ◽  
Dispersive Model ◽  
Shallow Water Models

AbstractNumerical technique for studying surface waves appearing under the motion of a submarine landslide is discussed. This technique is based on the application of the model of a quasi-deformable landslide and two shallow water models, namely, the classic (dispersion free) one and the completely nonlinear dispersive model of the second hydrodynamic approximation. Numerical simulation of surface waves generated by a large model landslide on the continental slope of the Black Sea near the Russian coast is performed. It is shown that the dispersion has a significant impact on the picture of propagation of tsunami waves on sufficiently long paths.

scholarly journals Diagnosing transit times on the northwestern North Atlantic continental shelf

2018 ◽  
Author(s):  
Krysten Rutherford ◽  
Katja Fennel
Keyword(s):  
North Atlantic ◽  
Gulf Of Maine ◽  
Circulation Model ◽  
Shelf Break ◽  
Genetic Connectivity ◽  
Western Boundary ◽  
Coastal Current ◽  
Scotian Shelf ◽  
Grand Banks ◽  
Transit Times

Abstract. The circulation in the northwestern North Atlantic Ocean is highly complex, characterized by the confluence of two major western boundary current systems and several shelf currents. Here we present the first comprehensive analysis of transport paths and timescales for the northwestern North Atlantic shelf, which is useful for estimating ventilation rates, describing circulation and mixing, characterizing the composition of water masses with respect to different source regions, and elucidating rates and patterns of biogeochemical processing, species dispersal and genetic connectivity. Our analysis uses dye and age tracers within a high-resolution circulation model of the region, divided into 9 sub-regions, to diagnose retention times, transport pathways, and transit times. Retention times are shortest on the Scotian Shelf (~ 3 months) where the inshore and shelf-break branches of the coastal current system result in high along-shelf transport to the southwest. Larger retention times are simulated on the Grand Banks (~ 4 months), in the Gulf of St. Lawrence (~ 12 months) and the Gulf of Maine (~ 6 months). Source water analysis shows that Scotian Shelf water is primarily comprised of waters from the Grand Banks and Gulf of St. Lawrence, with varying composition across the shelf. Contributions from the Gulf of St. Lawrence are larger at near-shore locations, whereas locations near the shelf break have larger contributions from the Grand Banks and slope waters. Waters from the deep slope have little connectivity with the shelf, because the shelf-break current inhibits transport across the shelf break. Grand Banks and Gulf of St. Lawrence waters are therefore dominant controls on biogeochemical properties, and on setting and sustaining planktonic communities on the Scotian Shelf.

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