The Bubble’s Wake: Localized Rebound of Kīlauea’s Summit Lava Lake Following Minor Bubble Bursts

Abstract:

One persistent mode of outgassing from Kīlauea’s summit lava lake, which has been active since 2008, is characterized by dome-shaped upwellings of incandescent lava several meters across on the lake surface. These phenomena usually occur a few times per minute during the lava lake’s typical north-to-south circulation regime, dampen and disappear within seconds, and produce few pyroclasts. Up until now, it has not been possible to determine if these upwellings were caused by the bursting of discrete bubbles or by rafts of smaller bubbles, though their slow speed and relative lack of pyroclasts suggested the latter.

However, observations of these phenomena during 2013–14 using high-speed (200–500 Hz) cameras found a surprising result. Each dome-shaped upwelling was, instead, the aftermath of the bursting of a discrete bubble, which broke through the surface crust a few tenths of a second before the related upwelling and was roughly one-quarter to one-half its size. Thus, these upwellings appear to be the rebound of the lava lake surface into the void created by relatively minor, meter-scale bubble bursts. In some instances, the rebound even develops into a liquid jet.

Rebound of the lava lake surface following wall rock collapses has been shown to be important for triggering transient explosive activity at Kīlauea since 2008. The dome-shaped upwellings described here are another example of lake-rebound dynamics at Kīlauea, though on a smaller scale. In light of the prevalence of these phenomena at Kīlauea, rebound of the magma column following disturbances at the magma free-surface could play a role in other volcanic systems as well.