If you check the time most say the fire started and the USGS report of a 1.3 quake, they are close. Since the depth is logged as 0, I would assume the gas explosion registered as an earthquake at 6:11:12 PM on 9/9/10 and that was the time it all erupted. It will be interesting to see what they find out. The fact that gas was reported at least one week before says something was going on.
Bob in Woodland Hills