My first response to a prediction like that would be to toss it out as vague.

If someone insisited that's how they wanted to make a prediction, then I guess the question you'd need to ask would be do they know about this numbering scheme? If they didn't then that leaves you in the position of having to interpret what they are trying to say, and interpreting it into a "F" number. If they are familiar with this scheme, then they know something about earthquakes, and would probably have more sense than to make a prediction based on political boundries, and wouldn't use it.

Michael