A study from New Zealand’s National Institute of Water and Atmospheric Research (NIWA) has mapped the immediate aftereffects of the January 2022 eruption of Hunga Tonga – Hunga Ha’apai, highlighting the risks of similar events.
The study, published in Nature Communications, is part of an international project, the NIWA-Nippon Foundation Tonga Eruption Seabed Mapping Project (TESMaP), which includes 13 partners from Tonga, New Zealand, Australia, Germany, the USA and the UK.
The eruption was the biggest atmospheric explosion recorded on Earth in more than 100 years, displacing almost 10km3 of sea floor and generating a tsunami that sent shockwaves around the world.
Following the eruption, scientists from NIWA sailed on RV Tangaroa to collect geological data, video footage, sea bed imagery and water column samples. Using this information, they were able to show the far-reaching ocean impacts of such a large eruption, including the widespread loss of sea floor life.
Dr Sarah Seabrook, biogeochemist at NIWA and lead author of the study, said, “The initial voyage has led to discoveries never before seen, reshaping our understanding of the impacts of volcanic eruptions on ocean ecosystems. Just one example is the role of underwater mountains (seamounts) providing a sheltering effect from the powerful sea floor density currents that smothered much of the sea floor around the volcano, wiping out sea floor life in the area, but left the seamounts relatively unscathed.
“Such refugia have been reported on land, where vegetation and people have been sheltered, but not in the ocean. But survival after the initial event is only the first hurdle. The eruption causes dramatic changes to nutrient and oxygen levels in the water which could have feedbacks that we are yet to understand. We do not know the timescale over which the sea floor communities in the Hunga Volcano may recover, but we think it may be aided by the recolonization of the life that survived near these seamounts. The only way to see if it has survived, and to what extent, is to revisit the area.”
According to Seabrook, most eruptions of submarine volcanoes go undetected or underreported with little data before or after eruptions. There is still much to be learned about the 22 mapped volcanoes in the Kingdom of Tonga, along with hundreds more along the Tonga-Tofua-Kermadec Arc, and numerous others worldwide.
Seabrook concluded, “Future monitoring, of both the volcanic edifice itself and the surrounding sea floor and habitats, is necessary to robustly determine the resilience and recovery of both human and natural systems to major submarine eruptions. It will also help more broadly assess the risks posed by the many similar submerged volcanoes that exist worldwide.”
Dr Isobel Yeo, a volcanologist based at the UK’s National Oceanography Centre (NOC) and lead scientist of the UK part of this international program, commented, “This work has highlighted the potential of offshore volcanoes to produce immense eruptions that pose a serious threat to coastal communities and subsea infrastructure, and highlights the urgent need for more research on and monitoring of these volcanic systems, not just in Tonga, but globally.”
Dr James Hunt, senior staff researcher at the National Oceanography Centre, added, “International partnerships were key to the success of the research. This complex project required the mobilization of a vessel immediately after the eruption and brought together a truly multidisciplinary science team. This could only be achieved through international collaborations, underlining a need to work across borders to understand volcanic hazards.”
For more key meteorological updates on the 2022 Hunga Tonga eruption, click here, and for a video on the mapping project, click here.
