The Eruption of Hunga Tonga Was a Disaster for Marine Ecosystems

In January 2022, the underwater volcano Hunga Tonga erupted in the Pacific Ocean. Jamie Perera, Midjourney, ESA

The eruption of the Hunga Tonga volcano in January 2022 not only had a significant impact on the upper atmosphere but also wreaked havoc on the marine environment. A recent study reveals that the ocean floor was completely devastated within a radius of 20 kilometers.

Approximately 2 years ago, the underwater volcano Hunga Tonga violently erupted. Now recognized as one of the most powerful explosive eruptions ever recorded, this event had a significant impact on the atmosphere: ashes, salt, water vapor, and other gases disturbed the composition of the upper atmosphere. The eruption is even suspected to have affected the climate of the year 2023, although this is a matter of debate.

The Devastated Ocean Floor Within a Radius of 20 Kilometers

Around Hunga Tonga, the ocean floor is, in places, covered by 20 metres of eruption-related deposits. Images of the seafloor reveal the virtual absence of life, except in a few areas that have been protected from density currents. Seabrook et al, 2023, Nature communications
Around Hunga Tonga, the ocean floor is, in places, covered by 20 metres of eruption-related deposits. Images of the seafloor reveal the virtual absence of life, except in a few areas that have been protected from density currents. Seabrook et al, 2023, Nature communications.

However, the atmosphere is not the only environment that was affected. The ocean floor also bore the brunt of this powerful eruption. A new study, published in the journal Nature Communications, reveals the extent of the damage to benthic ecosystems.

Researchers compared data collected before the eruption, between 2015 and 2017, and three months afterward. The data demonstrates that the volcano’s eruption completely destroyed a sizable portion of the ocean floor. The explosion lifted and displaced a massive amount of rocks and sediments (nearly 10 km3 in total), creating powerful density currents that swept everything within a 20-kilometer radius around Hunga Tonga and caused the massive mortality of organisms inhabiting the ocean floor.

Significant Impact on Marine Ecosystems

Only a few communities seem to have survived locally in areas protected by high topography, which acts as barriers against these currents resembling actual avalanches. Three months after the volcanic disaster, very fine ash particles were still observed in the water column. It is likely that their presence causes a disturbance in the medium-term supply of light, nutrients, and oxygen for marine ecosystems.