Anatomy of Some Atlantic Margin Sediment Slides and Some Comments on Ages and Mechanisms

Embley, R. W.

doi:10.1007/978-1-4613-3362-3_11

Cited by 63 publications

(58 citation statements)

References 27 publications

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“…The gradient of the line of connection between the outcrops sampled in the present study is 0.26 degrees. Even a slope of only 0.26 degrees (or less) is possible for debris flows to occur (Mountjoy et al, 1972;Carter, 1975;Middleton & Hampton, 1976;Flood et al, 1979;Embley, 1976Embley, , 1982 2007, 2012). But the palaeoslope at the time of deposition of these sediments is not known.…”

Section: Diamictite Formations Structure and Texturementioning

confidence: 99%

The origin of upper Precambrian diamictites, northern Norway: a case study applicable to diamictites in general

Molén¹

2017

Geologos

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Upper Precambrian diamictites in Varangerfjorden (northern Norway) have been examined for evidence of origin, whether glaciogenic, gravity flow or polygenetic. Studies of geomorphology, sedimentology and surface microtextures on quartz sand grains are integrated to provide multiple pieces of evidence for the geological agents responsible for the origin of the diamictites. The documented sedimentary and erosional structures, formerly interpreted in a glaciogenic context (e.g., diamict structure, pavements and striations) have been reanalysed. Field and laboratory data demonstrate that, contrary to conclusions reached in many earlier studies, the diamictites and adjacent deposits did not originate from glaciogenic processes. Evidence from macrostructures may occasionally be equivocal or can be interpreted as representing reworked, glacially derived material. Evidence from surface microtextures, from outcrops which are believed to exhibit the most unequivocal signs for glaciation, display no imprint at all of glaciogenic processes, and a multicyclical origin of the deposits can be demonstrated. The geological context implies (and no geological data contradict this) an origin by gravity flows, possibly in a submarine fan environment. This reinterpretation of the diamictites in northern Norway may imply that the palaeoclimatological hypothesis of a deep frozen earth during parts of the Neoproterozoic has to be revised.

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Section: Diamictite Formations Structure and Texturementioning

confidence: 99%

The origin of upper Precambrian diamictites, northern Norway: a case study applicable to diamictites in general

Molén¹

2017

Geologos

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“…The pioneer studies of the Saharan debris flow by Embley [1976Embley [ , 1982 Several genetic processes have been used to explain the E1 Golfo embayment (see further discussion), but the hypothesis of a giant landslide is widely accepted after Masson [1996] related it to a submarine debris avalanche. The E1 Golfo debris avalanche represents 3.1% of the volcanic edifice considering, according to Schmincke [1990], 3 a full prelandslide volume of 5500 km for the whole E1 Hierro.…”

Section: Landslides Around the Canary Islandsmentioning

confidence: 99%

The most recent megalandslides of the Canary Islands: El Golfo debris avalanche and Canary debris flow, west El Hierro Island

Úrgeles¹,

Canals²,

Baraza³

et al. 1997

J. Geophys. Res.

166

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Abstract. Two major landsliding events have been identified west of the island of E1 Hierro: The E1 Golfo debris avalanche and the Canary debris flow. These landslides were identified from swath bathymetry, seismic reflection, and TOpographic PArametric Sonar (TOPAS) data obtained in December 1994 during a cruise on board the Spanish R/V Hesperides. The E1 Golfo debris avalanche originated subaerially on the western flank of the island of E1 Hierro and has an associated 150 km 3 rock debris deposit on the base of slope. The Canary debris flow, which dislocated some 400 km 3 of sediment, resulted from a different failure originated between 3200 and 3700 m depth at the base of slope of the island of E1 Hierro. According to the studied data set, its source area seems to have been covered by the E1 Golfo debris avalanche deposit. The triggering of the E1 Golfo debris avalanche (between 136 and 21 ka) is related to tensional stresses on the rift zones of the island. These rift zones control the emplacement and morphology of the landslide scar. In the Canary Islands, a relation between landslide ages and island ages can be established, indicating a link between subsidence history, age of shield phases, and giant landslides.

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“…1). These previously known landslide complexes are well mapped from early studies (e.g., Embley, 1982;Cashman and Popenoe, 1985;O'Leary, 1986;Prior et al, 1986;Chaytor et al, 2012a), and occur within the various geologic zones with the exception of the carbonate zone. The combined source and deposit areas of these landslide complexes each exceed 3000 km 2 , and except for the Veatch Canyon landslide, the volume of material evacuated from each is greater than 100 km 3 .…”

Section: Local Landslide Sourcesmentioning

confidence: 89%

“…Submarine landslides along the U.S. Atlantic margin have been described and analyzed in a number of local (e.g., Embley, 1982;Cashman and Popenoe, 1985;O'Leary, 1986;Prior et al, 1986;Locat et al, 2010Locat et al, , 2013Chaytor et al, 2012a;Mulder et al, 2012) and regional (Booth and O'Leary, 1991;Booth et al, 1993;Twichell et al, 2009) studies. Past compilations of landslides along the U.S. Atlantic margin utilized a variety of geophysical imaging techniques, beginning with single-channel airgun and sparker seismic reflection profiles (Embley and Jacobi, 1977), to GLORIA sidescan backscatter and early lowresolution swath bathymetry (Booth et al, 1993), and higherresolution but incomplete swath bathymetry coverage of the margin (Chaytor et al, 2007;Twichell et al, 2009).…”

Section: Local Landslide Sourcesmentioning

confidence: 99%

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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Anatomy of Some Atlantic Margin Sediment Slides and Some Comments on Ages and Mechanisms

Cited by 63 publications

References 27 publications

The origin of upper Precambrian diamictites, northern Norway: a case study applicable to diamictites in general

The origin of upper Precambrian diamictites, northern Norway: a case study applicable to diamictites in general

The most recent megalandslides of the Canary Islands: El Golfo debris avalanche and Canary debris flow, west El Hierro Island

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

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