Geomorphic characterization of the U.S. Atlantic continental margin

Brink, Uri S. ten; Andrews, Brian D.; Chaytor, Jason D.

doi:10.1016/j.margeo.2012.12.008

Cited by 50 publications

(53 citation statements)

References 57 publications

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“…Previous studies on the U.S. Atlantic margin suggested that regional slope gradient does not necessarily correlate with landslide occurrence (e.g., Twichell et al, 2009 slope gradient and basic margin physiography have profound influences on depositional processes and the accumulation patterns of potentially unstable depocenters (Brothers et al, 2013a). Other factors such as weak layers, pore-fluid overpressures, and bottom stress (both transient and by salt tectonics) may also influence slope stability.…”

Section: Conditions That Contribute To Slope Failuresmentioning

confidence: 96%

“…Limited accommodation space during former sea level lowstands, and the proximity of the shelf edge to the steep upper continental slope (Brothers et al, 2013a) led to considerable sediment bypass to the lower slope. Poag (1992) estimated the volume of Pleistocene sediments on the shelf and upper slope to be 5% of the total sediments delivered to the margin and the volume of Pliocene sediments to be 10% of the total.…”

Section: Conditions That Contribute To Slope Failuresmentioning

confidence: 99%

“…Poag (1992) estimated the volume of Pleistocene sediments on the shelf and upper slope to be 5% of the total sediments delivered to the margin and the volume of Pliocene sediments to be 10% of the total. A self-organized feedback loop between slope failure, pore-fluid pressures and canyon head formation (Orange et al, 1994;Pratson and Coakley, 1996) caused most sediment to bypass the slope, and thus aided the construction of rough and steep canyon-dominated slope morphology (Poag, 1992;Pratson et al, 1994;O'Grady et al, 2000;Brothers et al, 2013a).…”

Section: Conditions That Contribute To Slope Failuresmentioning

confidence: 99%

“…1). The thickness of Quaternary sediments is likely controlled also by the physiography of the pre-Pleistocene margin (Brothers et al, 2013a, Section 2.1.1), which could have limited the accommodation space in parts of the margin and would have promoted sediment bypass to the deeper parts of the margin. Better monitoring of the seismic activity along the margin, and better mapping of buried shelf-edge deltas and the thickness of Quaternary sediments will help clarify the factors controlling the spatial distribution of landslides.…”

Section: Is Landslide Distribution Uniform In Space and Time?mentioning

confidence: 99%

“…1) reveals more subtle morphological variations, which are likely governed by the earlier sedimentary history of the margin (Brothers et al, 2013a). The steep Mesozoic reef bank beneath Georges Bank margin appears to have had a profound influence on the evolution and modern-day steepness of the slope, whereas Early Cenozoic stratigraphic packages along the upper and middle slope of Southern New England and the Hudson Apron had gentle, sigmoidal forms that are nearly maintained today (Brothers et al, 2013a).…”

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confidence: 99%

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Assessment of tsunami hazard to the U.S. Atlantic margin

et al. 2014

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Keywords: submarine landslides meteo-tsunami earthquakes and landslides probabilistic hazard assessment Tsunami hazard is a very low-probability, but potentially high-risk natural hazard, posing unique challenges to scientists and policy makers trying to mitigate its impacts. These challenges are illustrated in this assessment of tsunami hazard to the U.S. Atlantic margin. Seismic activity along the U.S. Atlantic margin in general is low, and confirmed paleo-tsunami deposits have not yet been found, suggesting a very low rate of hazard. However, the devastating 1929 Grand Banks tsunami along the Atlantic margin of Canada shows that these events continue to occur. Densely populated areas, extensive industrial and port facilities, and the presence of ten nuclear power plants along the coast, make this region highly vulnerable to flooding by tsunamis and therefore even lowprobability events need to be evaluated. We can presently draw several tentative conclusions regarding tsunami hazard to the U.S. Atlantic coast. Landslide tsunamis likely constitute the biggest tsunami hazard to the coast. Only a small number of landslides have so far been dated and they are generally older than 10,000 years. The geographical distribution of landslides along the margin is expected to be uneven and to depend on the distribution of seismic activity along the margin and on the geographical distribution of Pleistocene sediment. We do not see evidence that gas hydrate dissociation contributes to the generation of landslides along the U.S. Atlantic margin. Analysis of landslide statistics along the fluvial and glacial portions of the margin indicate that most of the landslides are translational, were probably initiated by seismic acceleration, and failed as aggregate slope failures. How tsunamis are generated from aggregate landslides remains however, unclear. Estimates of the recurrence interval of earthquakes along the continental slope may provide maximum estimates for the recurrence interval of landslide along the margin. Tsunamis caused by atmospheric disturbances and by coastal earthquakes may be more frequent than those generated by landslides, but their amplitudes are probably smaller. Among the possible far-field earthquake sources, only earthquakes located within the Gulf of Cadiz or west of the Tore-Madeira Rise are likely to affect the U.S. coast. It is questionable whether earthquakes on the Puerto Rico Trench are capable of producing a large enough tsunami that will affect the U.S. Atlantic coast. More information is needed to evaluate the seismic potential of the northern Cuba fold-and-thrust belt. The hazard from a volcano flank collapse in the Canary Islands is likely smaller than originally stated, and there is not enough information to evaluate the magnitude and frequency of flank collapse from the Azores Islands. Both deterministic and probabilistic methods to evaluate the tsunami hazard from the margin are available for application to the Atlantic margin, but their implementation requires more information than is c...

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Section: Conditions That Contribute To Slope Failuresmentioning

confidence: 96%

Section: Conditions That Contribute To Slope Failuresmentioning

confidence: 99%

Section: Conditions That Contribute To Slope Failuresmentioning

confidence: 99%

Section: Is Landslide Distribution Uniform In Space and Time?mentioning

confidence: 99%

mentioning

confidence: 99%

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Assessment of tsunami hazard to the U.S. Atlantic margin

et al. 2014

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Seabed fluid expulsion along the upper slope and outer shelf of the U.S. Atlantic continental margin

Ruppel

Kluesner

Brink

et al. 2014

Geophysical Research Letters

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[1] Identifying the spatial distribution of seabed fluid expulsion features is crucial for understanding the substrate plumbing system of any continental margin. A 1100 km stretch of the U.S. Atlantic margin contains more than 5000 pockmarks at water depths of 120 m (shelf edge) to 700 m (upper slope), mostly updip of the contemporary gas hydrate stability zone (GHSZ). Advanced attribute analyses of highresolution multichannel seismic reflection data reveal gascharged sediment and probable fluid chimneys beneath pockmark fields. A series of enhanced reflectors, inferred to represent hydrate-bearing sediments, occur within the GHSZ. Differential sediment loading at the shelf edge and warminginduced gas hydrate dissociation along the upper slope are the proposed mechanisms that led to transient changes in substrate pore fluid overpressure, vertical fluid/gas migration, and pockmark formation. Citation: Brothers, D.

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Gulf of Alaska continental slope morphology: Evidence for recent trough mouth fan formation

Swartz

Gulick

Goff

2015

Geochem Geophys Geosyst

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Glaciated continental shelves are host to numerous morphologic features that help understand past glacier dynamics. Southeastern Alaska is home to the St. Elias mountains, an active orogen that also hosts temperate marine glaciers. During glacial periods ice streams advance across the continental shelf, carving shelf-crossing troughs that reach the shelf edge. We use high-resolution multibeam data to develop the relationship between the Yakutat and Alsek Sea Valleys and the resulting continental slope morphology. The shelf and slope geomorphology can be divided into statistical groupings that relate to the relative balance of erosion and deposition. Our analysis indicates that only the Yakutat system has been able to build an incipient trough-mouth fan. The extreme sediment supply from this region was able to overwhelm the steep initial topography of the transform margin while further to the east sediment slope-bypass dominates. This analysis provides an extreme end member to existing studies of temperate glaciation along continental margins. The unique interplay between rapid uplift due to ongoing collision and the massive erosion caused by temperate glaciers provides for sedimentary flux far above most other systems.

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Geomorphic characterization of the U.S. Atlantic continental margin

Cited by 50 publications

References 57 publications

Assessment of tsunami hazard to the U.S. Atlantic margin

Assessment of tsunami hazard to the U.S. Atlantic margin

Seabed fluid expulsion along the upper slope and outer shelf of the U.S. Atlantic continental margin

Gulf of Alaska continental slope morphology: Evidence for recent trough mouth fan formation

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