Kilauea’s Fountaining Unveils the Underlying Drivers of Volcanic Eruptions

Kilauea has been erupting almost continuously for nearly 200 years, and volcanologists have observed many facets of Hawaii’s most active volcano. However, in the past year the volcano began producing frequent lava fountains.

The fountaining era commenced at dawn on December 23, 2024, with an eruption inside the Halema’uma’u summit crater. Since then, Kilauea has presented a recurring display of lava fountains, according to a recent Science publication. By September 2026, the volcano had generated 54 distinct fountains, some reaching heights of up to 457 meters.

While occasional lava fountains can occur during eruptions that last hours, days, months, or even years, repeated, distinct bursts separated by minutes to weeks are rare. At Kilauea, such clustered eruptions have occurred only three times since 1823, and never with this frequency.

The rarity of these episodic fountains means that knowledge about what triggers, sustains, and terminates them is limited, according to Ashton Flinders, a research geophysicist at the U.S. Geological Survey’s Hawaiian Volcano Observatory in Hilo, and his colleagues. Two prevailing hypotheses have been proposed: (1) dissolved water in magma rising from depth suddenly releases pressure, causing an explosive burst; or (2) a carbon dioxide‑rich foam atop trapped magma expands violently, akin to the froth released when a soda bottle is shaken.

Kilauea serves as an ideal natural laboratory for testing these hypotheses, the researchers note. The volcano has been intensively studied for decades, with continuous monitoring of seismic activity, temperature, low‑frequency acoustics, ground deformation, and gas emissions. These data are enabling scientists to construct an initial understanding of the processes involved.

Prior to each fountaining episode, the caldera floor was observed to swell and tilt, indicating magma accumulation beneath the surface. As the eruption progressed, a pattern emerged, first evident before the fourteenth fountain, characterized by a repeating sequence of minutes‑long seismic pulses and low‑frequency acoustic signals.

The research team interprets these signals as resulting from the buildup and release of trapped gases within magma, causing it to rise and fall through narrow vents like a piston. Notably, while sulfur dioxide was emitted, carbon dioxide levels were low, weakening the foam hypothesis.

This represents only an early glimpse into the phenomenon, and many questions remain, the authors conclude.

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