Hawaii’s Kilauea volcano has experienced 52 fountain eruptions as of last month, with the most violent spewing lava over 400 meters high. Researchers from the US Geological Survey, writing in Science, have documented these events to understand what triggers the dramatic liquid-rock displays.
How Kilauea Inflated Before the 2024 Fissure Opened
Volcanic activity in Hawaii is typically sedate. Lava usually flows slowly down mountain flanks, allowing people to walk out of its path. Yet Mount Etna, Iceland, and Hawaii occasionally produce violent fountains reaching several hundred meters into the air.
Kilauea stands out as Hawaii’s youngest and most active volcano. Even so, it recorded only three fountaining episodes between 1823 and recent years. That rarity sparked intensive structural study. Thirty-five separate monitoring stations track the site using seismic, infrasound, geodetic, gas, and visual and thermal cameras.
A major eruption in 2018 drained an underground lava reservoir. Refilling began steadily soon after. By 2019, the refill accelerated. The local peak inflated at over 22 cm annually. That rate doubled to 57 cm a year by 2023, spreading into a nearby caldera.
The ground expanded by half a meter a day immediately before the lava fountains started. In 2024, a swarm of earthquakes accompanied the opening of a vent. A 900-meter-long fissure formed, sending fountains 160 meters high over 13 hours. A second eruption followed less than a day later.
Why Scientists Disagree on What Powers the Molten Jets
Two primary hypotheses attempt to explain the mechanics behind volcanic fountaining. One model suggests that dissolved water stays trapped in pressurized magma until the liquid ascends to a shallow depth, turning to steam. This expansion fragments the magma, speeding its ascent and allowing more steam to escape in a jet.
An alternative theory points to carbon dioxide release. This view argues that escaping carbon dioxide forms a gas-magma foam at the top of the chamber. Once pressure hits a critical threshold, the gas drives the magma upward until the chamber empties.
The latest data from Kilauea challenges the carbon dioxide foam model. Carbon dioxide levels remained low across the entire eruption cycle. Meanwhile, sulfur dioxide levels rose during eruptions and dropped afterward while staying elevated throughout the monitoring period.
What the Summit Tilt Reveals About Eruption Timing
Predicting when fountains will restart remains difficult because seismic signals offer little warning. However, researchers identified a reliable physical indicator in surface deformation. Each eruption caused rapid deflation at Kilauea’s summit. This was followed by the slow refilling of the Halemaʻumaʻu magma reservoir.
The US Geological Survey noted that consecutive eruptions consistently triggered when the summit tilt reached specific levels. Although the baseline tilt associated with eruptions trended downward over time, the margin between individual events remained narrow. This pattern allowed researchers to issue timely alerts ahead of new activity.
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