The sequence of events around the epicentre of the 1929 Grand Banks earthquake: initiation of debris flows and turbidity current inferred from sidescan sonar

Piper, David J. W.; Cochonat, Pierre; Morrison, Martin L.

doi:10.1046/j.1365-3091.1999.00204.x

Cited by 418 publications

(318 citation statements)

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“…As well as forming debris avalanche or debris flow deposits, such events can evolve into poorly-sorted, mud-rich debris flows, or turbidity currents via flow dilution (c.f. Mulder & Cochonat 1996;Ilstad et al, 2004;Bryn et al, 2005), and may appear in marine sediments as thick (up to several metres; Rothwell et al, 1992), coarsegrained and far-reaching turbidites (>1000 km; Rothwell et al, 1992;Piper et al, 1999;Fine et al, 2005), with significant basal erosion (Garcia 1996;Wynn and Masson 2003;Masson et al, 2006;Hunt et al, 2011). Although widespread, the distribution of these deposits is ultimately subject to topographic controls, in contrast to tephra fallout deposits.…”

Section: Reworked Volcaniclastic Depositsmentioning

confidence: 99%

Construction of volcanic records from marine sediment cores: A review and case study (Montserrat, West Indies)

Cassidy

Watt

Palmer

et al. 2014

Earth-Science Reviews

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Detailed knowledge of the past history of an active volcano is crucial for the prediction of the timing, frequency and style of future eruptions, and for the identification of potentially at-risk areas. Subaerial volcanic stratigraphies are often incomplete, due to a lack of exposure, or burial and erosion from subsequent eruptions. However, many volcanic eruptions produce widelydispersed explosive products that are frequently deposited as tephra layers in the sea. Cores of marine sediment therefore have the potential to provide more complete volcanic stratigraphies, at least for explosive eruptions. Nevertheless, problems such as bioturbation and dispersal by currents affect the preservation and subsequent detection of marine tephra deposits.Consequently, cryptotephras, in which tephra grains are not sufficiently concentrated to form layers that are visible to the naked eye, may be the only record of many explosive eruptions.Additionally, thin, reworked deposits of volcanic clasts transported by floods and landslides, or during pyroclastic density currents may be incorrectly interpreted as tephra fallout layers, leading to the construction of inaccurate records of volcanism. This work uses samples from the volcanic island of Montserrat as a case study to test different techniques for generating volcanic eruption records from marine sediment cores, with a particular relevance to cores sampled in relatively proximal settings (i.e. tens of kilometres from the volcanic source) where volcaniclastic material may form a pervasive component of the sedimentary sequence. Visible volcaniclastic deposits identified by sedimentological logging were used to test the effectiveness of potential alternative volcaniclastic-deposit detection techniques, including point counting of grain types (component analysis), glass or mineral chemistry, colour spectrophotometry, grain size measurements, XRF core scanning, magnetic susceptibility and X-radiography. This study demonstrates that a set of time-efficient, non-destructive and high-spatial-resolution analyses (e.g. XRF core-scanning and magnetic susceptibility) can be used effectively to detect potential cryptotephra horizons in marine sediment cores. Once these horizons have been sampled, microscope image analysis of volcaniclastic grains can be used successfully to discriminate between tephra fallout deposits and other volcaniclastic deposits, by using specific criteria Page | 3 related to clast morphology and sorting. Standard practice should be employed when analysing marine sediment cores to accurately identify both visible tephra and cryptotephra deposits, and to distinguish fallout deposits from other volcaniclastic deposits.

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Section: Reworked Volcaniclastic Depositsmentioning

confidence: 99%

Construction of volcanic records from marine sediment cores: A review and case study (Montserrat, West Indies)

Cassidy

Watt

Palmer

et al. 2014

Earth-Science Reviews

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“…A single turbidity current can transport over ten times the annual sediment flux from all of the world's rivers (Talling et al 2007), and can be more than 200 km wide (see Table 1 of Talling 2014). They can reach speeds of , 20 m/s (, 70 km/h) on seafloor gradients of just 0.3u (Piper et al 1999). Other types of particle-laden flow (such as pyroclastic flows and snow avalanches) can reach such speeds, but do so on much steeper gradients.…”

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confidence: 99%

Key Future Directions For Research On Turbidity Currents and Their Deposits

Talling

Allin

Armitage

et al. 2015

Journal of Sedimentary Research

163

117

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Turbidity currents, and other types of submarine sediment density flow, redistribute more sediment across the surface of the Earth than any other sediment flow process, yet their sediment concentration has never been measured directly in the deep ocean. The deposits of these flows are of societal importance as imperfect records of past earthquakes and tsunamogenic landslides and as the reservoir rocks for many deep-water petroleum accumulations. Key future research directions on these flows and their deposits were identified at an informal workshop in September 2013. This contribution summarizes conclusions from that workshop, and engages the wider community in this debate. International efforts are needed for an initiative to monitor and understand a series of test sites where flows occur frequently, which needs coordination to optimize sharing of equipment and interpretation of data. Direct monitoring observations should be combined with cores and seismic data to link flow and deposit character, whilst experimental and numerical models play a key role in understanding field observations. Such an initiative may be timely and feasible, due to recent technological advances in monitoring sensors, moorings, and autonomous data recovery. This is illustrated here by recently collected data from the Squamish River delta, Monterey Canyon, Congo Canyon, and offshore SE Taiwan. A series of other key topics are then highlighted. Theoretical considerations suggest that supercritical flows may often occur on gradients of greater than , 0.6u. Trains of up-slope-migrating bedforms have recently been mapped in a wide range of marine and freshwater settings. They may result from repeated hydraulic jumps in supercritical flows, and dense (greater than approximately 10% volume) near-bed layers may need to be invoked to explain transport of heavy (25 to 1,000 kg) blocks. Future work needs to understand how sediment is transported in these bedforms, the internal structure and preservation potential of their deposits, and their use in facies prediction. Turbulence damping may be widespread and commonplace in submarine sediment density flows, particularly as flows decelerate, because it can occur at low (, 0.1%) volume concentrations. This could have important implications for flow evolution and deposit geometries. Better quantitative constraints are needed on what controls flow capacity and competence, together with improved constraints on bed erosion and sediment resuspension. Recent advances in understanding dilute or mainly saline flows in submarine channels should be extended to explore how flow behavior changes as sediment concentrations increase. The petroleum industry requires predictive models of longer-term channel system behavior and resulting deposit architecture, and for these purposes it is important to distinguish between geomorphic and stratigraphic surfaces

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“…Grand Banks, Newfoundland (Piper et al, 1999). Submarine landslides 52 can be far larger than any terrestrial landslide, and can involve the 53 movement of hundreds or even several thousands of cubic kilometres 54 of material (Hampton et al, 1996;Hühnerbach and Masson, 2004;55 Talling et al, 2007).…”

mentioning

confidence: 99%

Are large submarine landslides temporally random or do uncertainties in available age constraints make it impossible to tell?

et al. 2015

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Large (N~1 km 3 ) submarine landslides can potentially generate very destructive tsunamis and damage expensive 19 sea floor infrastructure. It is therefore important to understand their frequency and triggers, and whether their 20 frequency is likely to change significantly due to future climatic and sea level change. It is expensive to both 21 collect seafloor samples and to date landslides accurately; therefore we need to know how many landslides 22 we need to date, and with what precision, to answer whether sea level is a statistically significant control. Previ-23 ous non-statistical analyses have proposed that there is strong correlation between climate driven changes and 24 landslide frequency. In contrast, a recent statistical analysis by Urlaub et al. (2013) of a global compilation of 25 41 large (N1 km 3 ) submarine landslide ages in the last 30 ka concluded that these ages have a temporally random 26 distribution. This would suggest that landslide frequency is not strongly controlled by a single non-random global 27 factor, such as eustatic sea level. However, there are considerable uncertainties surrounding the age of almost all 28 large landslides, as noted by Urlaub et al. (2013). This contribution answers a key question that Urlaub et al. 29 (2013) posed, but could not address -are large submarine landslides in this global record indeed temporally ran-30 dom, or are the uncertainties in landslide ages simply too great to tell? We use simulated age distributions in 31 order to determine the significance of available age constraints from real submarine landslides. First, it is 32 shown that realistic average uncertainties in landslide ages of ±3 kyr may indeed result in a near-random distri-33 bution of ages, even where there are non-random triggers such as sea level. Second, we show how combination of 34 non-random landslide ages from just 3 different settings, can easily produce an apparently random distribution if 35 the landslides from different settings are out of phase. Third, if landslide frequency was directly proportional to 36 sea level, we show that at least 10 to 53 landslides would need to be dated perfectly globally -to show this cor-37 relation. We conclude that it is prudent to focus on well-dated landslides from one setting with similar triggers, 38 rather than having a poorly calibrated understanding of ages in multiple settings. (Hampton et al., 1996; Hühnerbach and Masson, 2004; 55 Talling et al., 2007). Perhaps the most remarkable aspect of large sub-56 marine landslides is that they typically can occur on very low gradients worldwide, which includes the last 120 ka (Fig. 1). This is the largest The analysis by Urlaub et al. (2013) included the often considerable un-136 certainties in landslide ages in this analysis (Fig. 1), unlike most previ- bin, and the number of bins with one, two or more landslide ages. 154It was found that there was no statistically significant difference be- 155tween the frequency of bins with 1, 2, 3 or more landslide ages, both 156 real and s...

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The sequence of events around the epicentre of the 1929 Grand Banks earthquake: initiation of debris flows and turbidity current inferred from sidescan sonar

Cited by 418 publications

References 23 publications

Construction of volcanic records from marine sediment cores: A review and case study (Montserrat, West Indies)

Construction of volcanic records from marine sediment cores: A review and case study (Montserrat, West Indies)

Key Future Directions For Research On Turbidity Currents and Their Deposits

Are large submarine landslides temporally random or do uncertainties in available age constraints make it impossible to tell?

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