New formulae for estimating lava flow volumes at Mt. Etna Volcano, Sicily |
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| Authors: | J B Murray N F Stevens |
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| Institution: | (1) Department of Earth Sciences, The Open University, Milton Keynes, MK7 6AA, UK e-mail: j.b.murray@open.ac.uk Fax: +44-1908-655151, GB |
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| Abstract: | A new data set of Etna lava flows erupted since 1868 has been compiled from eight topographic maps of the volcano published
at intervals since then. Volumes of 59 flows or groups of flows were measured from topographic difference maps. Most of these
volumes are likely to be considerably more accurate than those published previously. We cut the number of flow volumes down
to 25 by selecting those examples for which the volume of an individual eruption could be derived with the highest accuracy.
This refined data set was searched for high correlations between flow volume and more directly measurable parameters. Only
two parameters showed a correlation coefficient of 70% or greater: planimetric flow area A (70%) and duration of the eruption
D (79%). If only short duration (<18 days) flows were used, flow length cubed, L3, had a correlation coefficient of 98%. Using combinations of measured parameters, much more significant correlations with
volume were found. Dh had a correlation coefficient of 90% (h is the hydrostatic head of magma above the vent), and , 92% (where W is mean width and E is the degree of topographic enclosure), and a combination of the two , 97%. These latter formulae were used to derive volumes of all eruptions back to 1868 to compare with those from the complete
data set. Values determined from the formulae were, on average, lower by 16% (Dh), 7% (, and 19% .
Received: 30 November 1998 / Accepted: 20 June 1999 |
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| Keywords: | Lava flow Lava volume Lava output Mount Etna Time series Flow morphometry |
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