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The pumice raft-forming 2012 Havre submarine eruption was effusive

Citation

Manga, M and Fauria, KE and Lin, C and Mitchell, SJ and Jones, M and Conway, CE and Degruyter, W and Hosseini, B and Carey, R and Cahalan, R and Houghton, BF and White, JDL and Jutzeler, M and Soule, SA and Tani, K, The pumice raft-forming 2012 Havre submarine eruption was effusive, Earth and Planetary Science Letters, 489 pp. 49-58. ISSN 0012-821X (2018) [Refereed Article]

Copyright Statement

Copyright 2018 Elsevier B.V.

DOI: doi:10.1016/j.epsl.2018.02.025

Abstract

A long-standing conceptual model for deep submarine eruptions is that high hydrostatic pressure hinders degassing and acceleration, and suppresses magma fragmentation. The 2012 submarine rhyolite eruption of Havre volcano in the Kermadec arc provided constraints on critical parameters to quantitatively test these concepts. This eruption produced a >1 km3 raft of floating pumice and a 0.1 km3 field of giant (>1 m) pumice clasts distributed down-current from the vent. We address the mechanism of creating these clasts using a model for magma ascent in a conduit. We use water ingestion experiments to address why some clasts float and others sink. We show that at the eruption depth of 900 m, the melt retained enough dissolved water, and hence had a low enough viscosity, that strain-rates were too low to cause brittle fragmentation in the conduit, despite mass discharge rates similar to Plinian eruptions on land. There was still, however, enough exsolved vapor at the vent depth to make the magma buoyant relative to seawater. Buoyant magma was thus extruded into the ocean where it rose, quenched, and fragmented to produce clasts up to several meters in diameter. We show that these large clasts would have floated to the sea surface within minutes, where air could enter pore space, and the fate of clasts is then controlled by the ability to trap gas within their pore space. We show that clasts from the raft retain enough gas to remain afloat whereas fragments from giant pumice collected from the seafloor ingest more water and sink. The pumice raft and the giant pumice seafloor deposit were thus produced during a clast-generating effusive submarine eruption, where fragmentation occurred above the vent, and the subsequent fate of clasts was controlled by their ability to ingest water.

Item Details

Item Type:Refereed Article
Keywords:Submarine volcano, eruption, ocean
Research Division:Earth Sciences
Research Group:Geology
Research Field:Volcanology
Objective Division:Expanding Knowledge
Objective Group:Expanding Knowledge
Objective Field:Expanding Knowledge in the Earth Sciences
Author:Carey, R (Dr Rebecca Carey)
Author:Jutzeler, M (Dr Martin Jutzeler)
ID Code:125458
Year Published:2018
Funding Support:Australian Research Council (DE150101190)
Web of Science® Times Cited:1
Deposited By:Earth Sciences
Deposited On:2018-04-18
Last Modified:2018-05-02
Downloads:0

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