Do earthquakes produce folds on rocks?
No, earthquakes are sudden, often very energetic events which produce faults and discontinuities. There is a sharp break in the strata when subjected to a powerful earthquake. The folding of strata is a much more gradual process, where rock deep underground is subjected to enormous lateral pressure over millions of years. This pressure is caused by plate movements (continental drift). Earthquakes have a variety of causes, but the most violent ones are also caused by continental drift as one plate slides past another along a fault line. The San Andreas Fault in California is an example of this. One of the plates is moving, but friction holds it in place for a while, sometimes for many years. Pressure builds up until suddenly the friction force holding it in place gives way, and there is an earthquake as the moving plate slips forward for a few metres. For these reasons, geologists have never seen a newly created fold after an earthquake. It is impossible for one to form in so short a time.