That speed is also too fast to be explained by a phenomenon called true polar wander, in which the Earth's entire crust and mantle reorient, moving a different geographic region to the North Pole.
The transition zone seems to be slightly thinned which might indicate a higher mantle temperature in this region.
过渡区似乎稍微变薄，这可能表明这个区域的地幔温度较高。
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The CMB is not only the medium transferring thermal energy from core to mantle, but also the region in which the temperature and temperature gradient is the highest in the whole mantle.