Earth scientists have discovered how continents are slowly peeled from beneath, fuelling volcanic activity in an unexpected place: the oceans.

Researchers at the University of Southampton and the GFZ Helmholtz Centre for Geosciences, together with colleagues, have proposed a new explanation for a long-standing question in geosciences: Where do the continental remnants on volcanic oceanic islands come from? Geochemical analyses and modelling have revealed the following picture: When continents break apart, a wave of instability is created at a depth of more than a hundred kilometres. This “mantle wave” scrapes material from the underside of the continents along the base, which is then transported sideways into the Earth's mantle beneath the oceans. There, these remnants of continental roots feed volcanic eruptions in the ocean crust over millions of years. Sometimes the material travels more than a thousand kilometres from the continental interiors before it forms oceanic islands.

A recent study published in National Science Review has estimated the global biological nitrogen fixation from natural terrestrial ecosystems as 78.2–89.8 Tg N yr^-1, revealing an underestimation of this flux up to ~18% in existing Earth System Models (ESMs). The findings suggest many ESMs may overstate the nitrogen limitation or vegetation internal nitrogen recycling efficiency.