Experiments recreating the phenomenon in a lab found that this is the result of post-perovskite crystals, which form from perovskite. The alignment of these crystals determines their hardness, which then determines how fast seismic waves can move through them. This is in part because if you were to plunge down 2,700 kilometers (1,700 miles), you would be jump-scared by seismic waves that accelerate when they hit the threshold of the D” layer. For post-perovskite crystals to align with each other, the axes all have to be in the same position. Murakami thinks that convection of materials in the mantle (such as plumes rising and slavs sinking) is behind the deformation in the D” layer.