Lookup NU author(s): Dr Andy Large,
Professor Andrew Russell,
Dr Anne-Sophie Meriaux
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Subglacial volcanic activity generates glacier outburst floods (jökulhlaups) which constitute some of the world’s largest floods. These erode, transport and deposit enormous volumes of sediment, generating significant landscape change extending considerable distances beyond glacier margins. Accurate reconstruction of the characteristics and magnitude of palaeo-jökulhlaups is notoriously difficult, as emphasis is placed on the final (surface) landscape form. The 2010 Eyjafjallajökull eruption in Iceland provided a unique opportunity to quantify the evolution of proglacial geomorphology during a series of volcanogenic jökulhlaups. Time-lapse imager and repeat terrestrial laser scanning before, and directly after the 2010 eruption show that the jökulhlaup with the highest discharge was not coincident with the largest sediment flux and ice-proximal geomorphic change. Only 18% by volume of 17 x 106 m3 of net ice-proximal sediment deposition was related to the largest jökulhlaup occurring on April 14th 2010. A second significant jökulhlaup on April 15th deposited the majority of the sediment (67%), prior to extensive deposition by a series of still smaller jökulhlaups over the last 16 days of the eruption which deposited 14% of the total sediment. The geomorphological and sedimentary signatures of the largest jökulhlaups at the beginning of the 2010 Eyjafjallajökull eruption are not recorded at all in the surface topography. The ice-proximal, post-eruption land surface cannot therefore be used to reconstruct the characteristics or magnitudes of either of the two largest jökulhlaups which posed the greatest risk to surrounding areas. These findings allow us to revise the prevailing model which assumes a single flood peak associated with maximum sediment flux.
Author(s): Dunning SA, Large ARG, Russell AJ, Roberts MJ, Duller R, Woodward J, Mériaux A-S, Tweed FS, Lim M
Publication type: Article
Publication status: Published
Print publication date: 01/10/2013
Online publication date: 30/07/2013
Acceptance date: 24/06/2013
ISSN (print): 0091-7613
ISSN (electronic): 1943-2682
Publisher: Geological Society of America
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