KilaueaA lava fountain climbed over 400 metres.
Researchers at the US Geological Survey could forecast each eruption, though no seismic signal preceded them.
Each eruption deflates the summit, and refilling raises its tilt until it returns to similar levels, triggering the next fountain.
The data favour a steam-driven model over carbon dioxide foam, because carbon dioxide stayed low throughout.
Researchers in Science still cannot explain why a process running all cycle suddenly triggers fountains.
Sources: Ars Technica