Lava fountains remain a mystery

Volcanoes at Mount Etna, Hawaii and Iceland expel lava in dramatic fountains reaching several hundred metres high, but scientists do not yet understand what powers them.

Kilauea offers rare opportunity

Kilauea has had only three fountaining episodes since eighteen twenty-three despite being Hawaii's youngest and most active volcano. Researchers from the US Geological Survey studied recent eruptions with thirty-five data-gathering stations.

Magma reservoir refilled rapidly

After a major eruption in two thousand eighteen drained an underground lava reservoir, refilling accelerated from twenty-two centimetres a year in two thousand nineteen to fifty-seven centimetres a year by two thousand twenty-three.

Fountains reached four hundred metres

In two thousand twenty-four, a nine hundred-metre-long fissure opened, sending fountains one hundred sixty metres high over thirteen hours.

Scientists predicted eruptions

The US Geological Survey recognised that consecutive eruptions occurred when the summit tilt reached similar levels.

Two competing theories exist

One theory holds that water pressure fragments magma, allowing rapid ascent and steam escape. The alternative suggests carbon dioxide forms a magma-gas foam at the magma chamber roof, which escapes and drives magma upward until…

Evidence favours steam model

Carbon dioxide levels remained low throughout the eruption cycle, ruling out the foam theory. Sulphur dioxide rose during eruptions but stayed high throughout, suggesting the steam-driven model better explains the fountains, though why it suddenly…

Magnesium oxide shows cycles

Magnesium oxide fluctuated throughout the eruption cycle, consistent with eruptions depleting a reservoir then refilling with hot material. Other oxides rose over time, suggesting newly arriving material has distinct chemical composition.

More data still needed

Researchers acknowledged needing more data. Infrared sampling was difficult during fountaining eruptions, and the height of fountains made installing additional monitoring hardware unsafe. One camera was destroyed capturing images of falling molten rock.

“One camera notably sacrificed itself in order to bring us images of red-hot, semi-molten rock falling from the sky.”