What makes ocean volcanoes so important?
Many of our planet's volcanoes are hidden beneath the waves. But out of sight doesn’t mean out of mind! Subsea volcanoes are vital for ocean health, yet eruptions may also present hazards to people and infrastructure. Researchers at the National Oceanography Centre are tackling some of the biggest questions in volcano science, aiming to understand the important role they play in our oceans and climate, and reduce the risks from eruptions to vulnerable communities.
The vast majority of marine volcanoes remain unmapped, and almost none are monitored continuously in real time, creating a dangerous blind spot in the world's oceans. It means limits our ability to forecast when or where the next hazardous eruption might happen; leaving coastal communities and vital marine infrastructure vulnerable.
The underwater environment can complicate volcanic eruptions. In the deep-sea, the water pressure can suppress explosions, creating fascinating lava formations. However, in shallower or partially emergent volcanic systems water interactions can make eruptions more explosive and hazardous. Understanding this complicated interplay between the oceans and volcanoes is key to understanding the hazards posed by marine volcanoes, which may include explosions, tsunamis, pyroclastic density currents, lahars, and huge floating rafts of pumice that drift for thousands of kilometers.
How do underwater volcanoes benefit ocean ecosystems?
Many volcanoes support hydrothermal systems, which in turn are home to some of the most unique biological communities on Earth. Water and fluid circulating through the volcano is heated, sometimes to temperatures upward of 400°C by magma and hot rock beneath the volcano. As it reaches the seafloor minerals dissolved in the fluids precipitate, often forming magnificent hydrothermal chimney structures or “black smokers". These dissolved minerals also support unique ecosystems, which can service without sunlight, and these regions are one of the places scientists believe life could first have evolved on Earth.
These mineral-rich fluids also act like natural fertilisers for the ocean. They carry iron, silica, and other nutrients up to the surface waters, boosting biological activity and helping to keep our global ocean healthy and productive.
What are NOC's main areas of volcanic research?
Our research covers everything from volcanic processes and hazard assessment to geochemistry and mineral resources. We use cutting-edge technology and world-class marine facilities to address these complex questions head-on. Our team brings together experts from many fields; including geologists, geophysicists, engineers, and social scientists working as one.
Our research is helping to explain the drivers and processes operating in some of Earth's most powerful and explosive volcanic systems, known as caldera volcanoes. Calderas form when large eruptions remove enough material from the plumbing system beneath a volcano, that it collapsesinto the void left. Our research examines what triggers these catastrophic events and how they impact the seafloor, marine life, and communities.
Our work on the 2021/2022 Hunga Volcano eruption in The Kingdom of Tonga; the most explosive volcanic event this century revealed the fastest underwater debris flows ever measured, giving us an unprecedented look into these destructive events. While active research at Santorini and Kolumbo in the Aegean Sea aims to constrain the role hydrothermal fluids play in driving explosive eruptions, to better understand and forecast hazards.
Nearly every active ocean volcano hosts a hydrothermal system, where mixtures of seawater and magmatic liquids, travel through the volcanic crust before venting out on the seafloor. These fluids can seep out slowly or blast out dramatically from high-temperature vents.
As they travel, these fluids deposit critical minerals that are targets for deep-sea exploration. Our research focuses on how these mineral deposits form, evolve, and are structured both above and below the seafloor. Recent work on the Mid-Atlantic Ridge has given us incredible three-dimensional maps of these systems, revealing how and where hydrothermal fluids are dissolving and precipitating minerals in the subsurface.
Lahars and Landslides
About half the world's active land volcanoes are within 20 kilometers of the coast; this means huge amounts of volcanic material wash into the ocean every year through ash deposits and volcanic mudflows, known as lahars. We don't fully understand what happens when these flows hit the water yet; but this knowledge is vital for predicting their behavior and impact. Active research in St Vincent and the Grenadines is revealing how and where material enters the ocean, how it’s transported offshore, and the potential hazards this material may pose.
Our researchers also study volcanic landslides, which can trigger tsunamis and damage seafloor infrastructure. Our work at Anak Krakatau has helped to better understand how the volcanic island failed, generating a devastating tsunami that killed more than 400 people. Our work on flank instability continues to inform hazard assessments at marine volcanoes around the world.
Assessing Volcanic Hazards and Strengthening Resilience
Marine volcanic hazards come in many forms and can severely impact coastal communities, critical infrastructure, and ocean economies. Our research teams lead projects that examine volcanic landslides, tsunami generation, and threats to essential marine infrastructure; especially the submarine cables that power our global internet.
We're pioneering new ways to monitor ocean volcanoes; like using existing seafloor cables with optical-fibre sensing technology to detect hazards in real time. This research directly informs hazard assessments and helps strengthen community preparedness in active regions like the South Pacific, Caribbean, Indian Ocean, and Mediterranean Sea.
Understanding Volcanic Hotspots and Ocean Basin Evolution
Some volcanic systems; like those that formed the Galápagos and Hawaiian Islands , originate from hotspots driven by massive geological features called mantle plumes. By taking part in the International Ocean Discovery Programme, we're reconstructing millions of years of geological history with remarkable precision. Analysis of volcanic rocks from the North Atlantic is revealing how the mantle plume rising deep beneath Iceland has fluctuated and influenced deep ocean circulation and climate patterns over the last 50 million years .
What has this research achieved?
Researchers at the National Oceanography Centre have advanced understanding of marine volcanic processes, better constraining hazards and highlighting benefits. Their work has shed light on explosive eruptions, such as the 2021/22 Hunga Tonga eruption, and the role of hydrothermal systems in driving volcanic activity. Cutting-edge mapping has revealed how mineral-rich fluids circulate, fertilising the oceans and supporting unique ecosystems. Studies of lahars, landslides, and tsunamis are improving hazard forecasting and community resilience, while innovative monitoring using seafloor cables enhances real-time detection. By linking volcanic processes to ocean health, climate, and geology, this research is transforming knowledge of Earth’s hidden volcanoes.
This work helps protect vulnerable coastal communities and critical offshore infrastructure; offering real protection for real people. It also helps us assess the mineral resources needed for the low-carbon future that is essential for our planet's survival. We share our findings in scientific journals like Science, Nature Communications, and Geophysical Research Letters; and we work hand in hand with policy makes, emergency agencies and other stakeholders, ensuring our discoveries are put into practice to support communities around the globe.
How does NOC share this knowledge with communities that need it most?
We work directly with the communities and industries most vulnerable to volcanic hazards. We do this through workshops, strategic partnerships, and focused outreach; especially in Small Island Developing States (also knows as Large Ocean States) where the need is greatest. Our new projects include direct exchange programs with South Pacific communities facing immediate volcanic threats.
We also collaborate with industry partners and government agencies to understand and reduce the impacts of deep-sea mineral exploration and provide guidance on monitoring technologies. Through presentations at conferences and public forums, we make sure our research discoveries become actionable knowledge that helps protect communities, shape policy, and support sustainable ocean management around the world.
Impacts of the Most Explosive Volcanic Eruption Ever Recorded
In January 2022, the eruption of the submerged Hunga Volcano triggered fatal tsunamis and pressure waves that travelled around the planet.
New research led by NOC has shown that major impacts were also felt far below the sea surface, when erupted volcanic material plunged straight into the ocean. Joint lead-scientists on the new paper, Dr Mike Clare and Dr Izzy Yeo, discuss these impacts including how the eruption cut subsea cables that connected Tonga’s telecommunications to the rest of the world.
