I have a planet in mind that is highly hostile to basically everything around its equator but is more or less survivable everywhere else(hopefully ^v^). One of the ideas I have in mind for making the equator hell has been to make the hemispheres of the planet rotate in opposite directions. This would have the delightful effect of constant earthquakes, endless volcanic activity, and horrendous winds and storms. Yay! Only, I don't know what could even cause a planet to be like this, and am rather curious if it's at all possible.
What could cause a planet's hemispheres to rotate in opposite directions?