Earthquakes, movement of tectonic plates, etc. can shift the mass of the earth closer to or further from center. This speeds up or slows rotation, like when yo

Earthquakes, movement of tectonic plates, etc. can shift the mass of the earth closer to or further from center. This speeds up or slows rotation, like when you are spinning in a chair and pull your arms in. Some energy is probably also lost to tidal friction with the moon.