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Timing, origin and emplacement dynamics of mass flows offshore of SE Montserrat in the last 110 ka: implications for landslide and tsunami hazards, eruption history, and volcanic island evolution

Timing, origin and emplacement dynamics of mass flows offshore of SE Montserrat in the last 110 ka: implications for landslide and tsunami hazards, eruption history, and volcanic island evolution
Timing, origin and emplacement dynamics of mass flows offshore of SE Montserrat in the last 110 ka: implications for landslide and tsunami hazards, eruption history, and volcanic island evolution
Mass flows on volcanic islands generated by volcanic lava dome collapse and by larger volume flank collapse, can be highly dangerous locally and may generate tsunamis that threaten a wider area. It is therefore important to understand their frequency, emplacement dynamics and relationship to volcanic eruption cycles. The best record of mass flow on volcanic islands may be found offshore, where most material is deposited, and where intervening hemipelagic sediment aids dating. Here we analyse what is arguably the most comprehensive sediment core data set collected offshore from a volcanic island. The cores are located southeast of Montserrat, on which the Soufriere Hills volcano has been erupting since 1995. The cores provide a record of mass flow events during the last 110?ka. Older mass flow deposits differ significantly from those generated by the repeated lava dome collapses observed since 1995. The oldest mass flow deposit originated through collapse of the basaltic South Soufriere Hills at 103-110?ka, some 20-30?ka after eruptions formed this volcanic centre. A ~1.8?km3 blocky debris avalanche deposit that extends from a chute in the island shelf records a particularly deep-seated failure. It likely formed from a collapse of almost equal amounts of volcanic edifice and coeval carbonate shelf, emplacing a mixed bioclastic-andesitic turbidite in a complex series of stages. This study illustrates how volcanic island growth and collapse involved extensive, large-volume submarine mass flows with highly variable composition. Run-out turbidites indicate that mass flows are emplaced either in multiple stages or as single events.
Montserrat, mass flow, submarine, stratigraphy
1525-2027
385-406
Trofimovs, J.
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Talling, P.J.
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Fisher, J.K.
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Sparks, R.S.J.
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Watt, S.F.L.
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Hart, M.B.
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Smart, C.
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Le Friant, A.
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Cassidy, M.
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Moreton, S.G.
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Leng, M.J.
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Trofimovs, J.
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Talling, P.J.
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Fisher, J.K.
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Sparks, R.S.J.
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Watt, S.F.L.
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Hart, M.B.
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Smart, C.
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Le Friant, A.
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Cassidy, M.
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Moreton, S.G.
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Leng, M.J.
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Trofimovs, J., Talling, P.J., Fisher, J.K., Sparks, R.S.J., Watt, S.F.L., Hart, M.B., Smart, C., Le Friant, A., Cassidy, M., Moreton, S.G. and Leng, M.J. (2013) Timing, origin and emplacement dynamics of mass flows offshore of SE Montserrat in the last 110 ka: implications for landslide and tsunami hazards, eruption history, and volcanic island evolution. Geochemistry, Geophysics, Geosystems, 14 (2), 385-406. (doi:10.1002/ggge.20052).

Record type: Article

Abstract

Mass flows on volcanic islands generated by volcanic lava dome collapse and by larger volume flank collapse, can be highly dangerous locally and may generate tsunamis that threaten a wider area. It is therefore important to understand their frequency, emplacement dynamics and relationship to volcanic eruption cycles. The best record of mass flow on volcanic islands may be found offshore, where most material is deposited, and where intervening hemipelagic sediment aids dating. Here we analyse what is arguably the most comprehensive sediment core data set collected offshore from a volcanic island. The cores are located southeast of Montserrat, on which the Soufriere Hills volcano has been erupting since 1995. The cores provide a record of mass flow events during the last 110?ka. Older mass flow deposits differ significantly from those generated by the repeated lava dome collapses observed since 1995. The oldest mass flow deposit originated through collapse of the basaltic South Soufriere Hills at 103-110?ka, some 20-30?ka after eruptions formed this volcanic centre. A ~1.8?km3 blocky debris avalanche deposit that extends from a chute in the island shelf records a particularly deep-seated failure. It likely formed from a collapse of almost equal amounts of volcanic edifice and coeval carbonate shelf, emplacing a mixed bioclastic-andesitic turbidite in a complex series of stages. This study illustrates how volcanic island growth and collapse involved extensive, large-volume submarine mass flows with highly variable composition. Run-out turbidites indicate that mass flows are emplaced either in multiple stages or as single events.

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Published date: February 2013
Keywords: Montserrat, mass flow, submarine, stratigraphy
Organisations: Geology & Geophysics, Geochemistry, Marine Geoscience

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Local EPrints ID: 346916
URI: http://eprints.soton.ac.uk/id/eprint/346916
ISSN: 1525-2027
PURE UUID: 0190d450-0da0-411b-9e14-79f99ff6c975

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Date deposited: 11 Jan 2013 13:47
Last modified: 14 Mar 2024 12:43

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Contributors

Author: J. Trofimovs
Author: P.J. Talling
Author: J.K. Fisher
Author: R.S.J. Sparks
Author: S.F.L. Watt
Author: M.B. Hart
Author: C. Smart
Author: A. Le Friant
Author: M. Cassidy
Author: S.G. Moreton
Author: M.J. Leng

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