Well I don't want to get side tracked on a separate arguement that (you said correctly) lends itself to speculation (ie. what the behavioral reaction in the dog or person given circumstances x,y,z).

You didn't clearly define your position on whether or not you think "Dogs have a sixth sense that allows them to sense quakes before they happen". So I am not sure how to respond other than just saying:

My position was just that I think while its a fact that they do have superior hearing frequency range, and sense of smell, that the majority of thier advantage lies in that they pay attention to thier surroundings much more actively than most people.
(speculation incoming!) I would love to see if that dog could significanly pre-cog a quake against a human if they were both put into the same room and the person was told to just relax on the floor and do nothing but unwind for the next few hours with the dog. My guess is that the dog might beat the human to it by fractions of a second. (if anyone has access to university research funds, they should waste gov tax money doing this experiment)

"ben sisko" says his dogs can hear his moms car a block away and get exicted. My dogs do the same thing, usually when they are sitting in the living room resting while i watch tv. But alot of times I hear my wife's car coming long before the dogs do if I am just resting or doing something low key and the dog is playing with his bones. Point being that distraction (work/play/conversation) significanly impacts the ability to recognize signals that might otherwise be noticed.

thats probably it. thats just wikipedia though.