Predicting earthquakes is like predicting climate change. No physics behind it, but everybody is oh so confident! My favourite two clusters are now the Caribbean and Alaska. Forget California, they're bankrupt! :)
Anyway, these clusters show that things can go on a long time, and mean absolutely nothing. Of course, tomorrow, when there is a big earthquake there, I didn't say this! Just open this statement and forget the rest: There's going to be a big earthquake.