We learned in school that the earth is made of layers: the crust with tectonic plates and oceans, the mantle, and the hot liquid core. But wait, there's more! Deep beneath the surface, there are huge blobs of ...something. Scientists call them LLSVPs, or large low-shear-velocity provinces. But knowing they are there does not tell us what they are, or how they affect our world.
Over the years, better maps kept showing the same bloblike features. One huddles under Africa; the other is beneath the Pacific. They lurk where the planet’s molten iron core meets its rocky mantle, floating like mega-continents in the underworld. Their highest points may measure over 100 times the height of Everest. And if you somehow brought them to the surface, God forbid, they contain enough material to cover the entire globe in a lava lake roughly 100 kilometers deep.
“It would be like having an object in the sky, and asking, ‘Is that the moon?’ And people are like, no. ‘Is that the sun?’ No. ‘What is it?’ We don’t know!” said Vedran Lekić, a seismologist at the University of Maryland. “And whatever it is, it is intimately tied to the evolution of the Earth.”
The first mystery of these hulking, hidden seismic features is whether they’re made of different stuff than the rest of the Earth’s mantle. The second: How do these patterns in the deep leave traces on our surface world?
While we don't have all the answers, we have a few possibilities and we have ongoing research. Read what we know about the massive blobs, er, LLSVPs, at Quanta magazine. -via Metafilter, where you'll find more links.
(Image credit: Sanne.cottaar)