Ice-melt rates during volcanic eruptions within water-drained, low pressure subglacial cavities

Woodcock, Duncan Charles and Lane, Stephen John and Gilbert, Jennifer Susan (2016) Ice-melt rates during volcanic eruptions within water-drained, low pressure subglacial cavities. Journal of Geophysical Research: Solid Earth, 121 (2). pp. 648-662. ISSN 2169-9356

[img]
Preview
PDF (Woodcock et al 2016)
Woodcock_et_al_2016.pdf - Published Version
Available under License Unspecified.

Download (853kB)
[img]
Preview
PDF (Postprint)
Postprint.pdf - Accepted Version
Available under License Creative Commons Attribution-NonCommercial.

Download (381kB)
[img]
Preview
PDF (AGU Supporting-Information)
AGU_Supporting_Information.pdf - Other

Download (43kB)
[img]
Microsoft Excel (Supporting information)
Supporting_information.xls - Other
Available under License Creative Commons Attribution-NonCommercial.

Download (89kB)

Abstract

Subglacial volcanism generates proximal and distal hazards including large-scale flooding and increased levels of explosivity. Direct observation of subglacial volcanic processes is infeasible; therefore, we model heat transfer mechanisms during subglacial eruptions under conditions where cavities have become depressurized by connection to the atmosphere.We consider basaltic eruptions in a water-drained, low-pressure subglacial cavity, including the case when an eruption jet develops. Such drained cavities may develop on sloping terrain, where ice may be relatively shallow and where gravity drainage of meltwater will be promoted. We quantify, for the first time, the heat fluxes to the ice cavity surface that result from steam condensation during free convection at atmospheric pressure and from direct and indirect radiative heat transfer from an eruption jet. Our calculations indicate that the direct radiative heat flux from a lava fountain (a “dry” end-member eruption jet) to ice is c. 25 kW m-2 and is a minor component. The dominant heat transfer mechanism involves free convection of steam within the cavity; we estimate the resulting condensation heat flux to be c. 250 kW m-2. Absorption of radiation froma lava fountain by steamenhances convection, but the increase in condensing heat flux is modest at c. 25 kW m-2. Overall, heat fluxes to the ice cavity surface are likely to be no greater than c. 300 kW m-2. These are comparable with heat fluxes obtained by single phase convection of water in a subglacial cavity but much less than those obtained by two-phase convection.

Item Type:
Journal Article
Journal or Publication Title:
Journal of Geophysical Research: Solid Earth
Additional Information:
Accepted for publication in Journal of Geophysical Research. Solid Earth. Copyright 2016 American Geophysical Union. Further reproduction or electronic distribution is not permitted.
Uncontrolled Keywords:
/dk/atira/pure/subjectarea/aacsb/disciplinebasedresearch
Subjects:
ID Code:
78807
Deposited By:
Deposited On:
31 Mar 2016 08:02
Refereed?:
Yes
Published?:
Published
Last Modified:
22 Sep 2020 02:37