Rapid southward motion of the Hawaiian plume, followed by a sharp slowdown, causes the sharp bend in the Hawaiian-Emperor hotspot track.
Citation:
Hassan, R., Müller, R.D., Gurnis, M., Williams, S.E. and Flament, N., 2016, A rapid burst in hotspot motion through the interaction of tectonics and deep mantle flow, Nature, 533, 239-242.