Effects of a major typhoon on sediment accumulation in Fangliao Submarine Canyon, SW Taiwan

Hale, R. P.; Nittrouer, Charles A.; Liu, James T.; Keil, Richard G.; Ogston, A. S.

doi:10.1016/j.margeo.2012.07.008

Cited by 34 publications

(15 citation statements)

References 61 publications

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“…Wave heights of up to 10 m were recorded nearby on the 7th to 10th of August. Although failure postdates the strongest wave action (Hale et al, 2012), it may have led to delayed failure through cyclic loading. This second flow travelled for over 370 km to water depths of 4000 m (Carter et al, 2012;Gavey, 2012).…”

Section: Typhoon Morakot Taiwan 2009mentioning

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

207

184

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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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Section: Typhoon Morakot Taiwan 2009mentioning

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

207

184

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“…The in-situ geotechnical explorations only have been done in the shallow waters where the water depth not exceed 100 m. Furthermore, only a few studies mentioned the interaction between various geological processes (Hale et al 2012;Su et al 2012). Benefits from the support of the projects funded by MOST, CGS, and NEP, the acquisition of dense and accurate submarine information using different geophysical, geochemical, engineering approaches has opened up new possibilities for improving our understanding of submarine geohazards and potential seafloor instability Hsu et al 2018a, b;Lin et al 2018).…”

Section: Resultsmentioning

confidence: 99%

“…The distribution of coarse sediments in the shelf is presumed to be due to the coarse sediment delivered by Tsengwen and Erjen Rivers and the extension of the offshore barrier off Tainan. In the Lower Fangliao Basin, since the FSC has no connection to the river on land, it is speculated that coarse sediments were delivered by earthquake-or flooding-induced gravitational flows (Hale et al 2012;Su et al 2012). On the western slope of the Hengchun Ridge, the sediments are mainly composed by slates.…”

Section: Grain Sizementioning

confidence: 99%

“…7). Considering the study area is deeply influenced by turbidity currents, hyperpycnal flows, and debris flows (Huh et al 2009;Hale et al 2012;Su et al 2012), non-steady state profiles are frequently obstructing the use of excess 210 Pb as a geo-chronometer. We proposed that the spatial distribution of excess 210 Pb inventory can be used as a substitute proxy of sedimentation rates and it reveals that the sediments discharged from the Gaoping River were mainly deposited on the flank of the GSC, the Lower Fangliao Basin, and along the levee system of the Lower Reach of GSC and its extension to the north terminus of the Manila Trench.…”

Section: Spatial Distribution Of Excess 210 Pb Inventorymentioning

confidence: 99%

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Sedimentological characteristics and seafloor failure offshore SW Taiwan

Hsu

et al. 2018

Terr. Atmos. Ocean. Sci.

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In this study, analysis results reveal two main deposition zones are located at the flank of upper Gaoping Submarine Canyon and Lower Fangliao Basin offshore SW Taiwan. The non-event related sediments deposited in past 150 years (i.e., 632 Mt km -2 ) was delivered and transported from Gaoping River by suspension process with tides and coastal currents and gradually spread out offshore. Meanwhile, the total mass of accumulation sediments is 1922 Mt km -2 , accounting for 40% Gaoping River's sediment load and suggesting that the deposition process is mainly controlled by natural hazards. Sedimentation rates in much of the study area, except in the main deposition zones, are less than 0.5 cm yr -1 (5 m kyr -1 ). Compared with the studies at the instability seafloor caused by high sedimentation rates (~30 m kyr -1 ), the offshore southwestern Taiwan is relatively stable. In this study, we also discovered a series of sediment waves located on the upper continental slope between Gaoping and Fangliao Submarine Canyons, which is related to the creeping process on seafloor. In summary, our results reveal the fluid activities, existence of weak layers and earthquake triggering are potential factors which might induced seafloor failures offshore southwestern Taiwan.

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“…The coaction of rapid accumulation and under-consolidation of sediments with earthquake events, which are potential triggers of submarine land-42 A. A. Osadchiev et al: Transport of river sediments and associated submarine landslides slides, have been the subject of considerable research efforts (e.g., Hsu et al, 2008;Huh et al, 2009;Hale et al, 2012;Carter et al, 2012).…”

Section: Introductionmentioning

confidence: 99%

Transport and bottom accumulation of fine river sediments under typhoon conditions and associated submarine landslides: case study of the Peinan River, Taiwan

Osadchiev

Korotenko

Zavialov

et al. 2016

Nat. Hazards Earth Syst. Sci.

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Abstract.A combination of a three-dimensional Eulerian ocean circulation model (Princeton ocean model, POM) and a Lagrangian particle-tracking model (Surface-Trapped River Plume Evolution, STRiPE) is used to study the fate of fine river sediments discharged by the Peinan River at the southeastern coast of the island of Taiwan. The composite model is verified against in situ measurements and applied to simulate primary sediment deposition under freshet and typhoon discharge conditions of the Peinan River. It is shown that local wind plays a crucial role in sediment transport and settling in the coastal area through its influence on the river plume dynamics and turbulent mixing in the upper layer. Wind forcing conditions generally determine the location of the sediment deposit area, while its final pattern is defined by coastal circulation as modulated by the geometry of the coast and local bathymetry. In the study, region riverborne sediments are deposited to the sea floor, mainly in the shallow shelf areas. A significant portion of discharged fine sediments is moved offshore to the deeper ocean where it is further advected and dispersed by strong coastal circulation, mainly governed by the Kuroshio Current.The performed numerical experiments showed that sediment accumulation rate under typhoon conditions is about 2 orders of magnitude greater compared to freshet conditions. Based on the simulation results, we identified areas of continental shelf and continental slope adjacent to the Peinan River estuary which exhibit a high risk of formation of submarine landslides during and shortly after the typhoon events.

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Effects of a major typhoon on sediment accumulation in Fangliao Submarine Canyon, SW Taiwan

Cited by 34 publications

References 61 publications

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

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

Sedimentological characteristics and seafloor failure offshore SW Taiwan

Transport and bottom accumulation of fine river sediments under typhoon conditions and associated submarine landslides: case study of the Peinan River, Taiwan

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