Insights into the emplacement dynamics of volcanic landslides from high-resolution 3D seismic data acquired offshore Montserrat, Lesser Antilles.

Crutchley, Gareth J., Karstens, Jens , Berndt, Christian , Talling, P. J., Watt, S. F. L., Vardy, M. E., Hühnerbach, Veit, Urlaub, Morelia , Sarkar, Sudipta , Klaeschen, Dirk , Paulatto, M., LeFriant, A., Lebas, Elodie and Maeno, F. (2013) Insights into the emplacement dynamics of volcanic landslides from high-resolution 3D seismic data acquired offshore Montserrat, Lesser Antilles. Marine Geology, 335 . pp. 1-15. DOI 10.1016/j.margeo.2012.10.004.

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Abstract

We present results from the first three-dimensional (3D) marine seismic dataset ever collected over volcanic landslide deposits, acquired offshore of the Soufrière Hills volcano on the island of Montserrat in the Lesser Antilles. The 3D data enable detailed analysis of various features in and around these mass wasting deposits, such as surface deformation fabrics, the distribution and size of transported blocks, change of emplacement direction and erosion into seafloor strata. Deformational features preserved on the surface of the most recent debris avalanche deposit (Deposit 1) reveal evidence for spatially-variant deceleration as the mass failure came to rest on the seafloor. Block distributions suggest that the failure spread out very rapidly, with no tendency to develop longitudinal ridges. An older volcanic flank collapse deposit (Deposit 2) appears to be intrinsically related to large-scale secondary failure of seafloor sediments. We observe pronounced erosion directly down-slope of a prominent headwall, where translational sliding of well-stratified sediments was initiated. Deep-reaching faults controlled the form and location of the headwall, and stratigraphic relationships suggest that sliding was concurrent with volcanic flank collapse emplacement. We also identified a very different mass wasting unit between Deposit 1 and Deposit 2 that was likely emplaced as a series of particle-laden mass flows derived from pyroclastic flows, much like the recent (since 1995) phase of deposition offshore Montserrat but at a much larger scale. This study highlights the power of 3D seismic data in understanding landslide emplacement processes offshore of volcanic islands.

Highlights:

► 3D seismic data show new detail of volcanic landslide deposits offshore Montserrat. ► Volcanic flank collapse material has been diverted around seafloor topographic highs. ► This bending during emplacement has caused pronounced erosion into seafloor strata. ► Erosion can destabilize seafloor slopes, which then fail as translational slides. ► Block distributions and surface deformation give insight into debris avalanche style.

Document Type: Article
Additional Information: WOS:000315002100001
Keywords: submarine landslide; debris avalanche; volcanic flank collapse; 3D seismic imaging; Montserrat; SOUFRIERE HILLS VOLCANO; SUBMARINE LANDSLIDES; CANARY-ISLANDS; DEBRIS AVALANCHE; TSUNAMI GENERATION; WEST-INDIES; FLANK; FLOW; COLLAPSE; DEPOSITS
Research affiliation: OceanRep > The Future Ocean - Cluster of Excellence
OceanRep > GEOMAR > FB4 Dynamics of the Ocean Floor > FB4-GDY Marine Geodynamics
Kiel University
Refereed: Yes
Open Access Journal?: No
DOI etc.: 10.1016/j.margeo.2012.10.004
ISSN: 0025-3227
Projects: Future Ocean
Date Deposited: 22 Dec 2011 15:22
Last Modified: 11 Jan 2018 08:08
URI: http://oceanrep.geomar.de/id/eprint/13185

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