Seismic waves tell us that something unusual is happening in the lowermost few hundred kilometers of Earth’s mantle. Beneath Africa and the Pacific lie two enormous thermochemical structures known as Large Low-Shear-Velocity Provinces (LLSVPs). These “large blobs” are slower to transmit shear waves, but beyond that, their physical nature remains one of the biggest open questions …[Read More]
Bored by the Lower Mantle? Think Again!
Is the lower mantle boring? For a long time, the lower mantle was thought to be relatively featureless and uniform compared to the more dynamic upper mantle. But recent seismic observations are challenging that idea, especially when we look near the base of the mantle. Recent studies from Maureen Long’s group (Creasy et al. 2017, …[Read More]