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Lava tube morphology on Etna and evidence for lava flow emplacement mechanisms.

Calvari, Sonia and Pinkerton, Harry (1999) Lava tube morphology on Etna and evidence for lava flow emplacement mechanisms. Journal of Volcanology and Geothermal Research, 90 (3-4). pp. 263-280. ISSN 0377-0273

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Abstract

Lava tubes play a pivotal role in the formation of many lava flow fields. A detailed examination of several compound ‘a‘a lava flow fields on Etna confirmed that a complex network of tubes forms at successively higher levels within the flow field, and that tubes generally advance by processes that include flow inflation and tube coalescence. Flow inflation is commonly followed by the formation of major, first-order ephemeral vents which, in turn, form an arterial tube network. Tube coalescence occurs when lava breaks through the roof or wall of an older lava tube; this can result in the unexpected appearance of vents several kilometers downstream. A close examination of underground features allowed us to distinguish between ephemeral vent formation and tube coalescence, both of which are responsible for abrupt changes in level or flow direction of lava within tubes on Etna. Ephemeral vent formation on the surface is frequently recorded underground by a marked increase in size of the tube immediately upstream of these vents. When the lining of an inflated tube has collapsed, ‘a‘a clinker is commonly seen in the roof and walls of the tube, and this is used to infer that inflation has taken place in the distal part of an ‘a‘a lava flow. Tube coalescence is recognised either from the compound shape of tube sections, or from breached levees, lava falls, inclined grooves or other structures on the walls and roof. Our observations confirm the importance of lava tubes in the evolution of extensive pahoehoe and ‘a‘a flow fields on Etna.

Item Type: Article
Journal or Publication Title: Journal of Volcanology and Geothermal Research
Uncontrolled Keywords: lava flow ; lava tube ; tube coalescence ; flow inflation
Subjects: G Geography. Anthropology. Recreation > GE Environmental Sciences
Departments: Faculty of Science and Technology > Lancaster Environment Centre
ID Code: 21687
Deposited By: ep_ss_importer
Deposited On: 04 Feb 2009 13:38
Refereed?: Yes
Published?: Published
Last Modified: 26 Jul 2012 15:50
Identification Number:
URI: http://eprints.lancs.ac.uk/id/eprint/21687

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