I really don't know - As far as I've been able to analyse it there seems to be more ear tones before large quakes - they seem to come daily or multiple times a day.

I heard a good loud strong one the night before Hector quake...

I've tried to keep a log of these things - I just note the tone and keep an eye out - I haven't really noted anything other than - more ear tones, a quake is coming... I'm trying to be a bit more rigourous about keeping track of them. This happened just recently but I don't remember whick quake it was now... It might have been Peru which puts it pretty far away..

Canie