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On the timing and nature of the multiple phases of slope instability on Eastern Rockall Bank, Northeast Atlantic

On the timing and nature of the multiple phases of slope instability on Eastern Rockall Bank, Northeast Atlantic
On the timing and nature of the multiple phases of slope instability on Eastern Rockall Bank, Northeast Atlantic

One of the most challenging tasks when studying large submarine landslides is determining whether the landslide was initiated as a single large event, a chain of events closely spaced in time or multiple events separated by long periods of time as all have implications in risk assessments. In this study we combine new multichannel seismic profiles and new sediment cores with bathymetric data to test whether the Rockall Bank Slide Complex, offshore western Ireland, is the composite of multiple slope collapse events and, if so, to differentiate them. We conclude that there have been at least three voluminous episodes of slope collapse separated by long periods of slope stability, a fourth, less voluminous event, and possibly a fifth more localized event. The oldest event, Slide A (200 km3), is estimated to be several hundred thousand years old. The second event, Slide B (125 km3), took place at the same location as slide A, reactivating the same scar, nearly 200 ka ago, possibly through retrogression of the scarp. Slide C (400 km3) took place 22 ka ago and occurred further north from the other slides. Slide D was a much smaller event that happened 10 ka ago, while the most recent event, albeit very small scale, took place within the last 1,000 years. This study highlights the need to thoroughly investigate large slide complexes to evaluate event sequencing, as seismic studies may hide multiple small-scale events. This work also reveals that the same slide scarps can be reactivated and generate slides with different flow behaviors.

bottom currents, British Irish Ice Sheet, debrite, flow transformation, multiphase slope collapse, Rockall Bank Slide Complex
1525-2027
Georgiopoulou, A.
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Krastel, S.
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Finch, N.
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Zehn, K.
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McCarron, S.
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Huvenne, V. A.I.
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Haughton, P. D.W.
05a79dc5-ebc5-46c5-b1b3-b816dbca57df
Shannon, P. M.
bc4ab42c-4b4b-4a12-9761-cc80f148cd03
Georgiopoulou, A.
cd508a3f-54d1-4334-ba9b-936e8fd42336
Krastel, S.
3f5620f7-1f0d-4429-9a50-5f72663edd4d
Finch, N.
325cd511-2077-4a3b-8182-18a730f7b06d
Zehn, K.
53362f2a-a19a-4424-869a-d10399a0e12b
McCarron, S.
1a75c9be-54b3-48e5-a21d-9fda1d5763c3
Huvenne, V. A.I.
f22be3e2-708c-491b-b985-a438470fa053
Haughton, P. D.W.
05a79dc5-ebc5-46c5-b1b3-b816dbca57df
Shannon, P. M.
bc4ab42c-4b4b-4a12-9761-cc80f148cd03

Georgiopoulou, A., Krastel, S., Finch, N., Zehn, K., McCarron, S., Huvenne, V. A.I., Haughton, P. D.W. and Shannon, P. M. (2018) On the timing and nature of the multiple phases of slope instability on Eastern Rockall Bank, Northeast Atlantic. Geochemistry, Geophysics, Geosystems. (doi:10.1029/2018GC007674).

Record type: Article

Abstract

One of the most challenging tasks when studying large submarine landslides is determining whether the landslide was initiated as a single large event, a chain of events closely spaced in time or multiple events separated by long periods of time as all have implications in risk assessments. In this study we combine new multichannel seismic profiles and new sediment cores with bathymetric data to test whether the Rockall Bank Slide Complex, offshore western Ireland, is the composite of multiple slope collapse events and, if so, to differentiate them. We conclude that there have been at least three voluminous episodes of slope collapse separated by long periods of slope stability, a fourth, less voluminous event, and possibly a fifth more localized event. The oldest event, Slide A (200 km3), is estimated to be several hundred thousand years old. The second event, Slide B (125 km3), took place at the same location as slide A, reactivating the same scar, nearly 200 ka ago, possibly through retrogression of the scarp. Slide C (400 km3) took place 22 ka ago and occurred further north from the other slides. Slide D was a much smaller event that happened 10 ka ago, while the most recent event, albeit very small scale, took place within the last 1,000 years. This study highlights the need to thoroughly investigate large slide complexes to evaluate event sequencing, as seismic studies may hide multiple small-scale events. This work also reveals that the same slide scarps can be reactivated and generate slides with different flow behaviors.

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Georgiopoulou et al revised - Accepted Manuscript
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More information

Accepted/In Press date: 4 December 2018
e-pub ahead of print date: 11 December 2018
Additional Information: An edited version of this paper was published by AGU. Copyright (2018) American Geophysical Union.”
Keywords: bottom currents, British Irish Ice Sheet, debrite, flow transformation, multiphase slope collapse, Rockall Bank Slide Complex

Identifiers

Local EPrints ID: 428449
URI: http://eprints.soton.ac.uk/id/eprint/428449
ISSN: 1525-2027
PURE UUID: 6cf8bc38-07e7-4be6-8c2a-f5529b500103
ORCID for V. A.I. Huvenne: ORCID iD orcid.org/0000-0001-7135-6360

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Date deposited: 27 Feb 2019 17:30
Last modified: 28 Apr 2022 01:53

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Contributors

Author: A. Georgiopoulou
Author: S. Krastel
Author: N. Finch
Author: K. Zehn
Author: S. McCarron
Author: V. A.I. Huvenne ORCID iD
Author: P. D.W. Haughton
Author: P. M. Shannon

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