Emplacement of pyroclastic deposits offshore Montserrat from 3D seismic data.

Karstens, Jens , Crutchley, Gareth J., Berndt, Christian , Talling, B. J., Watt, S. F. L., Hühnerbach, V., Le Friant, A., Lebas, Elodie and Trofimovs, J. (2013) Emplacement of pyroclastic deposits offshore Montserrat from 3D seismic data. Journal of Volcanology and Geothermal Research, 257 . pp. 1-11. DOI 10.1016/j.jvolgeores.2013.03.004.

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Abstract

During the current (1995–present) eruptive phase of the Soufrière Hills volcano on Montserrat, voluminous pyroclastic flows entered the sea off the eastern flank of the island, resulting in the deposition of well-defined submarine pyroclastic lobes. Previously reported bathymetric surveys documented the sequential construction of these deposits, but could not image their internal structure, the morphology or extent of their base, or interaction with the underlying sediments. We show, by combining these bathymetric data with new high-resolution three dimensional (3D) seismic data, that the sequence of previously detected pyroclastic deposits from different phases of the ongoing eruptive activity is still well preserved. A detailed interpretation of the 3D seismic data reveals the absence of significant (>3 m) basal erosion in the distal extent of submarine pyroclastic deposits. We also identify a previously unrecognized seismic unit directly beneath the stack of recent lobes. We propose three hypotheses for the origin of this seismic unit, but prefer an interpretation that the deposit is the result of the subaerial flank collapse that formed the English's Crater scarp on the Soufrière Hills volcano. The 1995–recent volcanic activity on Montserrat accounts for a significant portion of the sediments on the southeast slope of Montserrat, in places forming deposits that are more than 60 m thick, which implies that the potential for pyroclastic flows to build volcanic island edifices is significant.

Document Type: Article
Additional Information: WOS:000319848700001
Keywords: Volcanic island; Pyroclastic flow; Debris avalanche; 3D seismic data; Seismic facies; Soufrière Hills; Montserrat; SOUFRIERE HILLS; JC 45/46; VOLCANO; LESSER ANTILLES; LAVA DOME; WEST-INDIES; JULY 2003; SEA; FAILURE; FLOWS; COLLAPSE; ERUPTIONS
Research affiliation: OceanRep > The Future Ocean - Cluster of Excellence
OceanRep > GEOMAR > FB4 Dynamics of the Ocean Floor > FB4-GDY Marine Geodynamics
Refereed: Yes
Open Access Journal?: No
DOI etc.: 10.1016/j.jvolgeores.2013.03.004
ISSN: 0377-0273
Projects: Future Ocean
Expeditions/Models/Experiments:
Date Deposited: 23 Nov 2012 09:56
Last Modified: 08 Aug 2017 12:03
URI: http://oceanrep.geomar.de/id/eprint/19270

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