Why doesn't the elastic rebound theory satisfacorily explain all earthquakes?

Answer 1

No theory adequately explains observed facts. That is one of the reasons they are called theories. In Physics there are the theoretical endpoints of elastic and inelastic conditions. All conditions lie somewhere in between the endpoints. When a condition approaches an endpoint its behavior mimics the theoretical endpoint condition and variations from the ideal can be ignored. Refinements in the theory lead to better predictions of actual behavior, usually at the expense of other factors. That is the way of Science; real behavior is complicated and simple explanations don't answer all the aspects of a problem.