Just hours before the end of the Piton de la Fournaise eruption on Wednesday, March 25, 2026, a scientific mission was conducted off the lava flow. Initial observations by experts confirm intense activity at the interface between the lava and the ocean, with two lava entries into the sea and water temperatures exceeding 40°C, opening new avenues for study.
Significant smoke was still rising as a multidisciplinary team of scientists approached the lava platform formed at the sea entry off Sainte-Rose. Geologists, geochemists, and specialists from the Biolave program conducted a preliminary survey of the area on a semi-rigid boat.
Researchers from the universities of Lyon I and Clermont, along with an Irish scientist, used a spectrometer to measure the composition of volcanic plumes. Atmospheric samples were also taken to analyze particles and gases in the air.
“We identified two main lava outlets with strong plumes,” explained scientist Alain Barrère, involved in the Biolave program. The plume consists mainly of water vapor, hydrochloric acid (HCl), and fine particles.
At sea, these entry points appear to be associated with marked underwater phenomena. “We found two very hot water channels, over 40°C, likely linked to underwater outpourings,” Barrère further described. Water samples were taken along a perpendicular axis to the platform for further analysis.
The encounter of lava with the ocean caused a thermal shock of over 1,150 degrees, partially heating the ocean about twenty meters off La Réunion. This event created a small black sand beach downstream of the fallout, noted Nicolas Villeneuve from the University of La Réunion’s Volcanological Observatory.
In addition to scientific measurements, the mission aimed to visually document this volcanic episode. Teams from the Volcano Observatory and the Volcanism Documentation and Dissemination Center, along with Alain Barrère, were present to capture images and records.
These observations supplement ongoing research on the interactions between lava and the marine environment during the eruption. Scientists remain vigilant for any phenomena similar to the 2007 event, such as the upwelling of deep-sea fish.
As the eruption nears its end, data collected during this mission should enhance understanding of these spectacular interactions at the heart of Reunionese volcanism.
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Tags: Volcano, Piton de la Fournaise, Biolave Mission, Lava Flow, Atmosphere, Gas
