Cathryn;

You're pretty much on the money here. Aftershocks are inevitable but assigning a probability is anybodies' guess. There's a standard model for California but it doesn't apply elsewhere.

My personal opinion is that aftershocks end fairly soon, depending on the size of the main shock. But others better qualified than I say aftershocks can last for years.

If that's the case, evaluation becomes nearly impossible. All I could say is "hit or miss" in that case. Which isn't too helpful.

Roger