Submarine Volcanoes

Scientists estimate that at least 80% of the world's volcanism occurs in the oceans!

The Kermadec Arc, extending 1220km to the northeast of New Zealand, consists of at least 30 volcanic centres. Most volcanoes are entirely submarine, with only the Kermadec Islands projecting above sea level.

How do submarine volcanoes form in the Kermadec Arc?

The collision between tectonic plates results in subduction of the Pacific plate (including the oceanic crust) below the Australasian plate. This causes extension behind the subduction zone and backarc basins form.

At certain depths, usually around 200km, there is melting of the subducted materials. This produces magmas that rise buoyantly into the overlying crust. Periodically these erupt on Earth's surface and form arc volcanoes.

Most of the volcanic centres of the Kermadec contain one or more volcanoes that rival Ruapehu and Taranaki volcanoes in size. For detailed information about Kermadec and other volcanoes in New Zealand go here.

Many Kermadec Arc volcanoes have active hydrothermal vents, of interest in undersea prospecting, and for studying life in the deep.

Learn more about mapping the ocean floor.

Understanding the structure and dynamics of undersea volcanoes is also important in order to predict the risk of tsunamis that may be caused by them.