Until now, conventional wisdom is that the spreading of plates is typically driven by distant gravity forces as denser parts of the plates sink back into the Earth. However, the driving force behind the separation of the Atlantic plates has remained a mystery because the Atlantic ocean is not surrounded by dense, sinking plates. In 2016, a scientific experiment was set in the middle of the Atlantic Ocean. 39 seismometers were placed at the bottom of the ocean across the Mid-Atlantic Ridge.
Seismologists have imaged the layers inside Earth down to 700 km depth and found evidence of an upsurge of matter in the mantle – the material between the Earth’s crust and its core. Upwellings beneath ridges have been thought to originate from much shallower depths of around 60 km, however, the new observations provide evidence that upwellings are likely to originate from much deeper. The result is part of the PI-LAB (Passive Imaging of the Lithosphere-Asthenosphere Boundary) experiment and the EURO-LAB (Experiment to Unearth the Rheological Oceanic Lithosphere-Asthenosphere Boundary. It is one of only a few experiments of this scale ever conducted in the oceans.
The experiment is funded by the European Research Council (ERC) and Natural Environment Research Council (UK). Further reading is available online.