Disappearing plates: a planetary magic trick (IMAGE)
Caption
Subducting ocean plates seen in cold, sinking (top) and warm, rising (bottom) mantle rock produce a consistent seismic signal in S-wave models, but this consistent signal disappears when comparing P-wave models. Some iron-bearing minerals are more compressible during the crossover which effects their compressible (P-wave) velocity, but not their shear (S-wave) velocity. Since P-wave models are consistent at the top and bottom of the mantle, this disappearing act appears confined to the mid-mantle where the iron spin crossover is predicted to occur.
Credit
Grace Shephard
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License
CC BY-NC