“Megathrust quakes like Chile’s are so huge, and cause such a giant release of energy, that they change the shape of the Earth. In the case of Chile’s subduction quake, the planet became slightly denser and more compact. Mass was pulled closer to the Earth’s center as one plate was thrust under the other. And that affected the Earth’s spin. It made the planet spin slightly faster, to be precise, and shortened the length of the Earth day” (io9)