Emplacement of pyroclastic deposits offshore Montserrat: Insights from 3D seismic data

Karstens, J.; Crutchley, G.J.; Berndt, C.; Talling, P.J.; Watt, S.F.L.; Huhnerbach, V.; Friant, A. Le; Lebas, E.; Trofimovs, J.. 2013 Emplacement of pyroclastic deposits offshore Montserrat: Insights from 3D seismic data. Journal of Volcanology and Geothermal Research, 257. 1-11. 10.1016/j.jvolgeores.2013.03.004

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Official URL: http://dx.doi.org/10.1016/j.jvolgeores.2013.03.004

Abstract/Summary

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.

Item Type:	Publication - Article
Digital Object Identifier (DOI):	10.1016/j.jvolgeores.2013.03.004
ISSN:	03770273
Additional Keywords:	Volcanic island; Pyroclastic flow; Debris avalanche; 3D seismic data; Seismic facies; Soufrière Hills; Montserrat
Date made live:	21 May 2013 08:40 +0 (UTC)
URI:	https://nora.nerc.ac.uk/id/eprint/502018

Item Type:

Publication - Article

Digital Object Identifier (DOI):

10.1016/j.jvolgeores.2013.03.004

ISSN:

03770273

Additional Keywords:

Volcanic island; Pyroclastic flow; Debris avalanche; 3D seismic data; Seismic facies; Soufrière Hills; Montserrat

Date made live:

21 May 2013 08:40 +0 (UTC)

URI:

https://nora.nerc.ac.uk/id/eprint/502018