Mike, I'm just assuming that since there were large foreshocks...M>6..that something was moving. The foreshocks are precursory by definition, so there was a precursor by simple logic. As for Cascadia, I was just thinking out loud...it is a subduction zone (although probably very different than the Loyalty one), and it has the slow earthquakes every 14 months (??). I don't know anything special about Cascadia...just what I read here, and what I bump into as an AGU member once in a while (EOS etc.).
Chris