Bubble formation, surfacing and bursting at Halema'uma'u lava lake in 2018-implications on dynamics of lava lake outgassing
Abstract
Halema'uma'u lava lake disappeared from Kilauea's summit caldera in the wake of the 2018 Lower East Rift Zone eruption on the flanks of Kilauea. A final monitoring campaign of the lake's surface in early 2018 secured a valuable dataset constraining the physical processes of lava lake outgassing. Following hour-long periods of quiescent lava rise, the lake level drops within considerably shorter time, characterized by the violent release of gas. Investigation in the gas release mechanism can ultimately help to better understand gas accumulation processes beneath the surface of the lava lake.
Gas release takes place in the form of minute-to-hour long spattering events on the lake surface. Spattering is characterized by the release of gas bubbles through the lake surface and consists of a minority of meter-sized bubbles and a majority of decimeter-sized bubbles. Gas bubbles can be divided in three different physical regimes: I) bubbles floating beneath the surface, being too weak to break through the thin crust, II) bubbles bursting through the surface, producing characteristic bubble film droplets, and, III) bubble bursts followed by a jet of liquid lava. Bubble bursts and lava jets were monitored with a high speed camera; linear relationships between both bubble and jet velocity and ejecta height of bubbles and jets can be described. The observed regime of simultaneous escape of small, medium and large sized bubbles during spattering events suggest a combination of two of the three controversially discussed outgassing mechanism at lava lakes (gas pistoning through shallow accumulation of gas; rise of large, 10s of m sized gas slugs; dynamic pressure equilibration at the base of the conduit causing cyclic lava fluctuations): our results indicate both accumulation of cm-sized gas bubbles beneath the surface of the lava lake and subsequent coalescence to dm-sized bubbles as well as a simultaneous rise of up to several m-sized gas slugs through the conduit.- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2018
- Bibcode:
- 2018AGUFM.V14A..04H
- Keywords:
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- 3037 Oceanic hotspots and intraplate volcanism;
- MARINE GEOLOGY AND GEOPHYSICSDE: 3075 Submarine tectonics and volcanism;
- MARINE GEOLOGY AND GEOPHYSICSDE: 3618 Magma chamber processes;
- MINERALOGY AND PETROLOGYDE: 8428 Explosive volcanism;
- VOLCANOLOGY