An analogue study of the influence of solidification on the advance and surface thermal signature of lava flows

Garel, Fanny, Kaminski, Edouard, Tait, Steve and Limare, Angela 2014. An analogue study of the influence of solidification on the advance and surface thermal signature of lava flows. Earth and Planetary Science Letters 396 , pp. 46-55. 10.1016/j.epsl.2014.03.061

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Abstract

The prediction of lava flow advance and velocity is crucial during an effusive volcanic crisis. The effusion rate is a key control of lava dynamics, and proxies have been developed to estimate it in near real-time. The thermal proxy in predominant use links the satellite-measured thermal radiated power to the effusion rate. It lacks however a robust physical basis to allow time-dependent modeling. We investigate here through analogue experiments the coupling between the spreading of a solidifying flow and its surface thermal signal. We extract a first order behavior from experimental results obtained using polyethylene glycol (PEG) wax, that solidifies abruptly during cooling. We find that the flow advance is discontinuous, with relatively low supply rates yielding long stagnation phases and compound flows. Flows with higher supply rates are less sensitive to solidification and display a spreading behavior closer to that of purely viscous currents. The total power radiated from the upper surface also grows by stages, but the signal radiated by the hottest and liquid part of the flow reaches a quasi-steady state after some time. This plateau value scales around half of the theoretical prediction of a model developed previously for the spreading and cooling of isoviscous gravity currents. The corrected scaling yields satisfying estimates of the effusion rate from the total radiated power measured on a range of basaltic lava flows. We conclude that a gross estimate of the supply rate of solidifying flows can be retrieved from thermal remote-sensing, but the predictions of lava advance as a function of effusion rate appears a more difficult task due to chaotic emplacement of solidifying flows.

Item Type:	Article
Date Type:	Publication
Status:	Published
Schools:	Earth and Environmental Sciences
Subjects:	Q Science > QE Geology
Uncontrolled Keywords:	lava flows; analogue experiments; solidification during emplacement; thermal remote-sensing
Publisher:	Elsevier
ISSN:	0012-821X
Date of Acceptance:	28 March 2014
Last Modified:	27 Feb 2019 14:03
URI:	https://orca.cardiff.ac.uk/id/eprint/59108

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