Consequences of the El-Asnam earthquakes: Turbidity currents and slumps on the Algerian margin (Western Mediterranean)

El-Robrini, Maâmar; Gennesseaux, M.; Mauffret, A.

doi:10.1007/bf02281635

Cited by 35 publications

(25 citation statements)

References 8 publications

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“…The ground noise increased for 5 minutes and then the cable ruptured at a depth of 1470 m (El-Robrini et al 1985). Assuming that the turbidity current started at the shelf break, the estimated velocity of the turbidity current was 10 m s -1 , an estimate comparable to that determined at the Nice margin (Gennesseaux et al 1980).…”

Section: Comparisons With Other Turbidity Current Velocity Measurementsmentioning

confidence: 78%

“…Bourcart and Glangeaud (1956) and Heezen and Ewing (1955) believe that the breaks in submarine cables were caused by the motion of a landslide detached from the shelf edge by the earthquake and transformed into a strong turbidity current, which swept out across the Balearic abyssal plain, rather than directly by earthquake movements. Turbidity current velocities are 20.5 m s -1 between the two cables closest to shore (Heezen and Ewing 1956), 3.6 m s -1 between two more remote cables (Bourcart and Glangeaud 1956) and 14.9 m s -1 between the shelf edge and the nearest broken cable (El-Robrini et al 1985) (Fig. 3b).…”

Section: Comparisons With Other Turbidity Current Velocity Measurementsmentioning

confidence: 99%

“…3b). For comparison, cable breaks associated with a turbidity current triggered by the Orléansville earthquake (Heezen and Ewing 1955;Bourcart and Glangeaud 1956;El-Robrini et al 1985) are displayed on the same figure (black dots). Note the parallel curves between turbidity current velocities for the Pingtung and Orléansville earthquakes.…”

Section: Comparisons With Other Turbidity Current Velocity Measurementsmentioning

confidence: 99%

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Turbidity Currents, Submarine Landslides and the 2006 Pingtung Earthquake off SW Taiwan

Hsu¹,

Kuo²,

Lo³

et al. 2008

Terr. Atmos. Ocean. Sci.

195

106

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Submarine landslides or slumps may generate turbidity currents consisting of mixture of sediment and water. Large and fast-moving turbidity currents can incise and erode continental margins and cause damage to artificial structures such as telecommunication cables on the seafloor. In this study, we report that eleven submarine cables across the Kaoping canyon and Manila trench were broken in sequence from 1500 to 4000 m deep, as a consequence of submarine landslides and turbidity currents associated with the 2006 Pingtung earthquakes offshore SW Taiwan. We have established a full-scale scenario and calculation of the turbidity currents along the Kaoping canyon channel from the middle continental slope to the adjacent deep ocean. Our results show that turbidity current velocities vary downstream ranging from 20 to 3.7 and 5.7 m s -1 , which demonstrates a positive relationship between turbidity current velocity and bathymetric slope. The violent cable failures happened in this case evidenced the destructive power of the turbidity current to seafloor or underwater facilities that should not be underestimated.

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Section: Comparisons With Other Turbidity Current Velocity Measurementsmentioning

confidence: 78%

Section: Comparisons With Other Turbidity Current Velocity Measurementsmentioning

confidence: 99%

Section: Comparisons With Other Turbidity Current Velocity Measurementsmentioning

confidence: 99%

See 1 more Smart Citation

Turbidity Currents, Submarine Landslides and the 2006 Pingtung Earthquake off SW Taiwan

Hsu¹,

Kuo²,

Lo³

et al. 2008

Terr. Atmos. Ocean. Sci.

195

106

View full text Add to dashboard Cite

show abstract

“…The inverted seismic moment, M 0 = 2.2 9 10 27 dyn cm, is more than 5 times the largest published CMT in the area, but fails to characterize the event as a great subduction zone earthquake. The seismic character of the event is also confirmed by its abundant aftershocks, both locally EWING, 1952, 1955;HOUTZ, 1962;EL-ROBRINI et al, 1985;BOUHADAD et al, 2004).…”

Section: Scenario 7: the Western Luzon Earthquake Of 14 February 1934mentioning

confidence: 85%

Tsunami Simulations for Regional Sources in the South China and Adjoining Seas

Okal

Synolakis

Kalligeris

2010

Pure Appl. Geophys.

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We present 14 scenarios of potential tsunamis in the South China Sea and its adjoining basins, the Sulu and Sulawezi Seas. The sources consist of earthquake dislocations inspired by the the study of historical events, either recorded (since 1900) or described in historical documents going back to 1604. We consider worst-case scenarios, where the size of the earthquake is not limited by the largest known event, but merely by the dimension of the basin over which a coherent fault may propagate. While such scenarios are arguably improbable, they may not be impossible, and as such must be examined. For each scenario, we present a simulation of the tsunami's propagation in the marine basin, exclusive of its interaction with the coastline. Our results show that the South China, Sulu and Sulawezi Seas make up three largely independent basins where tsunamis generated in one basin do not leak into another. Similarly, the Sunda arc provides an efficient barrier to tsunamis originating in the Indian Ocean. Furthermore, the shallow continental shelves in the Java Sea, the Gulf of Thailand and the western part of the South China Sea significantly dampen the amplitude of the waves. The eastern shores of the Malay Peninsula are threatened only by the greatest-and most improbable-of our sources, a mega-earthquake rupturing all of the Luzon Trench. We also consider two models of underwater landslides (which can be triggered by smaller events, even in an intraplate setting). These sources, for which there is both historical and geological evidence, could pose a significant threat to all shorelines in the region, including the Malay Peninsula.

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“…The calculated flow velocities were 20.5 m/s between the first two cable breaks and 14.9 m/s between the two more distal cables. The 1980 El-Asnam earthquake (M W 7.3) in Algeria also damaged a cable at a water depth of 1470 m (El-Robrini et al, 1985). Assuming that the damage to the cable was caused by a turbidity current that started at the shelf break, a flow velocity of 10 m/s can be estimated for this event.…”

Section: Offshore Taiwan Pingtung Earthquakes 2006mentioning

confidence: 99%

How are subaqueous sediment density flows triggered, what is their internal structure and how does it evolve? Direct observations from monitoring of active flows

Talling

Paull

Piper

2013

Earth-Science Reviews

200

181

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Subaqueous sediment density flows are one of the volumetrically most important processes for moving sediment across our planet, and form the largest sediment accumulations on Earth (submarine fans). They are also arguably the most sparely monitored major sediment transport processes on our planet. Significant advances have been made in documenting their timing and triggers, especially within submarine canyons and delta-fronts, and freshwater lakes and reservoirs, but the sediment concentration of flows that run out beyond the continental slope has never been measured directly. This limited amount of monitoring data contrasts sharply with other major types of sediment flow, such as river systems, and ensure that understanding submarine sediment density flows remains a major challenge for Earth science. The available monitoring data define a series of flow types whose character and deposits differ significantly. Large (N 100 km 3 ) failures on the continental slope can generate fast-moving (up to 19 m/s) flows that reach the deep ocean, and deposit thick layers of sand across submarine fans. Even small volume (0.008 km 3 ) canyon head failures can sometimes generate channelised flows that travel at N 5 m/s for several hundred kilometres. A single event off SE Taiwan shows that river floods can generate powerful flows that reach the deep ocean, in this case triggered by failure of recently deposited sediment in the canyon head. Direct monitoring evidence of powerful oceanic flows produced by plunging hyperpycnal flood water is lacking, although this process has produced shorter and weaker oceanic flows. Numerous flows can occur each year on river-fed delta fronts, where they can generate up-slope migrating crescentic bedforms. These flows tend to occur during the flood season, but are not necessarily associated with individual flood discharge peaks, suggesting that they are often triggered by delta-front slope failures. Powerful flows occur several times each year in canyons fed by sand from the shelf, associated with strong wave action. These flows can also generate up-slope migrating crescentic bedforms that most likely originate due to retrogressive breaching associated with a dense near-bed layer of sediment. Expanded dilute flows that are supercritical and fully turbulent are also triggered by wave action in canyons. Sediment density flows in lakes and reservoirs generated by plunging river flood water have been monitored in much greater detail. They are typically very dilute (b 0.01 vol.% sediment) and travel at b 50 cm/s, and are prone to generating interflows within the density stratified freshwater. A key objective for future work is to develop measurement techniques for seeing through overlying dilute clouds of sediment, to determine whether dense near-bed layers are present. There is also a need to combine monitoring of flows with detailed analyses of flow deposits, in order to understand how flows are recorded in the rock record. Finally, a source-to-sink approach is needed because the character of subm...

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Consequences of the El-Asnam earthquakes: Turbidity currents and slumps on the Algerian margin (Western Mediterranean)

Cited by 35 publications

References 8 publications

Turbidity Currents, Submarine Landslides and the 2006 Pingtung Earthquake off SW Taiwan

Turbidity Currents, Submarine Landslides and the 2006 Pingtung Earthquake off SW Taiwan

Tsunami Simulations for Regional Sources in the South China and Adjoining Seas

How are subaqueous sediment density flows triggered, what is their internal structure and how does it evolve? Direct observations from monitoring of active flows

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