Giant blobs deep inside Earth are 'evolving by themselves'

We finally know where two giant blobs in Earth's middle layer came from - and they're a mismatched pair.

- WORDS STEPHANIE PAPPAS

These strange regions in Earth's mantle, known as 'large low-velocity provinces' (LLVPs), are actually chunks of Earth's crust that have sunk into the mantle over the past billion years. Scientists have long known that there are LLVPs, one below the Pacific Ocean and the other below Africa. In these regions, seismic waves from earthquakes travel one per cent to three per cent more slowly than they do in the rest of the mantle. Scientists believe they may affect the planet's magnetic field because of the way they influence heat flow from Earth's core.