Reunion, a French island in the western Indian Ocean, sits above one of Earth’s mantle plumes – a tower of superheated rock that ascends from the deep mantle.
In 2012, a team of geophysicists and seismologists set out to map the plume, using a giant network of seismometers across the depths of the Indian Ocean seafloor. Their results show that the mantle is stranger than expected. The plume isn’t a simple column. Instead, a massive mantle plume ‘tree’ rises from the edges of the Earth’s core, with superheated branchlike structures appearing to grow diagonally out of it. As these branches approach the crust, they seem to sprout smaller, vertically rising branches.
Another recent discovery found additional structures in the plumes under Africa.
No one has ever directly seen a plume; they are inferred to exist with seismic waves. They emanate from earthquakes that dive through Earth’s inner regions before curving back towards the surface. As these waves travel, the geological bodies they pass through alter their speed and direction allowing scientist to figure out what exists within the Earth.
Seismologists have also discovered two giant blobs of material – one beneath Africa, the other below the Pacific that are located at the boundary between the mantle and the core.
The African giant blob, located 2,900 kilometers below the surface, grows up from its middle to form a trunk reaching a depth of 1,500 kilometers. The top of the trunk, named the cusp, appears to grow thick branches of hot matter from its western and eastern extremities. These grow diagonally upward until they reach a depth of 1,000 to 800 kilometers; then the tops of these branches sprout vertically thin branches.
https://www.wired.com/story/a-huge-subterranean-tree-is-moving-magma-to-earths-surface/