The Unsolved Mystery of the Earth Blobs – Eos
Scientists believe these blobs play a role in many of the processes of the deep Earth, including plate tectonics and volcanism. “It was very clear in those models from the get-go that at the bottom of Earth’s mantle, nearly halfway to the center, there were these huge zones where the waves traveled more slowly,” said Ed Garnero, professor of Earth and space exploration at Arizona State University. A group of researchers led by Linguo Yuan at Academia Sinica in Taiwan analyzed measurements from GPS stations across the globe over 16 years and found that the Earth tide wasn’t what they expected: It seemed to be off-kilter just above where the blobs were located.
Source: eos.org