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Combinations of volcanic-flank and seafloor-sediment failure offshore Montserrat, and their implications for tsunami generation

Combinations of volcanic-flank and seafloor-sediment failure offshore Montserrat, and their implications for tsunami generation
Combinations of volcanic-flank and seafloor-sediment failure offshore Montserrat, and their implications for tsunami generation
Recent seafloor mapping around volcanic islands shows that submarine landslide deposits are common and widespread. Such landslides may cause devastating tsunamis, but accurate assessment of tsunami hazard relies on understanding failure processes and sources. Here we use high-resolution geophysical data offshore from Montserrat, in the Lesser Antilles, to show that landslides around volcanic islands may involve two fundamentally different sources of sediment (island-flank and larger seafloor-sediment failures), and can occur in multiple stages. A combination of these processes produces elongate deposits, with a blocky centre (associated with island-flank collapse), surrounded by a smoother-surfaced deposit that is dominated by failed seafloor sediment. The failure of seafloor sediment is associated with little marginal accumulation, and involves only limited downslope motion. Submarine landslide deposits with similar blocky and smoothsurfaced associations are observed in several locations worldwide, but the complex emplacement processes
implied by this morphological relationship can only be revealed by high-resolution geophysical data. Such complexity shows that the volume of landslide deposits offshore of volcanic islands cannot simply be used in tsunami models to reflect a single-stage collapse of primary volcanic material. By applying predictive equations
for tsunami amplitude to investigate general scenarios of volcanic island landslide generation, we show that the tsunami hazard associated with volcanic island collapse remains highly significant. Volcanic flank failures, even if relatively small, may generate large local tsunamis, but associated seafloor sediment failures, even if they have a much greater volume, have a substantially lower potential for tsunami generation.
landslide, tsunami, volcano, Montserrat, submarine sediment slide, flank collapse
0012-821X
228-240
Watt, S.F.L.
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Talling, P.J.
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Vardy, M.E.
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Heller, V.
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Huhnerbach, V.
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Urlaub, Morelia
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Sarkar, Sudipta
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Masson, D.G.
edd44c8b-38ca-45fb-8d0d-ac8365748a45
Henstock, T.J.
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Minshull, T.A.
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Paulatto, M.
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Le Friant, A
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Lebas, E
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Berndt, C.
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Crutchley, G
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Karstens, J
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Stinton, A
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Maeno, F
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Watt, S.F.L.
76f594eb-9252-4a8b-822f-be71038b18db
Talling, P.J.
1cbac5ec-a9f8-4868-94fe-6203f30b47cf
Vardy, M.E.
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Heller, V.
e0c25be3-5a51-4101-9830-e7e66cd075ba
Huhnerbach, V.
1ea7cdde-a6fd-4749-b880-504c958c588c
Urlaub, Morelia
f5a21932-9794-4008-b0a9-72bb366098b8
Sarkar, Sudipta
336e2653-e4d9-44f4-bb72-d9b1a9ca22e9
Masson, D.G.
edd44c8b-38ca-45fb-8d0d-ac8365748a45
Henstock, T.J.
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Minshull, T.A.
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Paulatto, M.
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Le Friant, A
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Lebas, E
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Berndt, C.
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Crutchley, G
cc61aa32-2113-4ce7-9e93-e3dd2608a148
Karstens, J
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Stinton, A
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Maeno, F
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Watt, S.F.L., Talling, P.J., Vardy, M.E., Heller, V., Huhnerbach, V., Urlaub, Morelia, Sarkar, Sudipta, Masson, D.G., Henstock, T.J., Minshull, T.A., Paulatto, M., Le Friant, A, Lebas, E, Berndt, C., Crutchley, G, Karstens, J, Stinton, A and Maeno, F (2012) Combinations of volcanic-flank and seafloor-sediment failure offshore Montserrat, and their implications for tsunami generation. Earth and Planetary Science Letters, 319-320, 228-240. (doi:10.1016/j.epsl.2011.11.032).

Record type: Article

Abstract

Recent seafloor mapping around volcanic islands shows that submarine landslide deposits are common and widespread. Such landslides may cause devastating tsunamis, but accurate assessment of tsunami hazard relies on understanding failure processes and sources. Here we use high-resolution geophysical data offshore from Montserrat, in the Lesser Antilles, to show that landslides around volcanic islands may involve two fundamentally different sources of sediment (island-flank and larger seafloor-sediment failures), and can occur in multiple stages. A combination of these processes produces elongate deposits, with a blocky centre (associated with island-flank collapse), surrounded by a smoother-surfaced deposit that is dominated by failed seafloor sediment. The failure of seafloor sediment is associated with little marginal accumulation, and involves only limited downslope motion. Submarine landslide deposits with similar blocky and smoothsurfaced associations are observed in several locations worldwide, but the complex emplacement processes
implied by this morphological relationship can only be revealed by high-resolution geophysical data. Such complexity shows that the volume of landslide deposits offshore of volcanic islands cannot simply be used in tsunami models to reflect a single-stage collapse of primary volcanic material. By applying predictive equations
for tsunami amplitude to investigate general scenarios of volcanic island landslide generation, we show that the tsunami hazard associated with volcanic island collapse remains highly significant. Volcanic flank failures, even if relatively small, may generate large local tsunamis, but associated seafloor sediment failures, even if they have a much greater volume, have a substantially lower potential for tsunami generation.

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More information

Published date: 15 February 2012
Additional Information: Funded by NERC: How is ash dispersed in the ocean around volcanoes? (NE/F010478/1)
Keywords: landslide, tsunami, volcano, Montserrat, submarine sediment slide, flank collapse
Organisations: Geology & Geophysics, Ocean and Earth Science, Marine Geoscience, Civil Maritime & Env. Eng & Sci Unit

Identifiers

Local EPrints ID: 208973
URI: http://eprints.soton.ac.uk/id/eprint/208973
ISSN: 0012-821X
PURE UUID: 6f8e2bbf-0d25-419a-9214-1240de2ccc95
ORCID for T.J. Henstock: ORCID iD orcid.org/0000-0002-2132-2514
ORCID for T.A. Minshull: ORCID iD orcid.org/0000-0002-8202-1379

Catalogue record

Date deposited: 24 Jan 2012 15:38
Last modified: 15 Mar 2024 03:04

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Contributors

Author: S.F.L. Watt
Author: P.J. Talling
Author: M.E. Vardy
Author: V. Heller
Author: V. Huhnerbach
Author: Morelia Urlaub
Author: Sudipta Sarkar
Author: D.G. Masson
Author: T.J. Henstock ORCID iD
Author: T.A. Minshull ORCID iD
Author: M. Paulatto
Author: A Le Friant
Author: E Lebas
Author: C. Berndt
Author: G Crutchley
Author: J Karstens
Author: A Stinton
Author: F Maeno

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