I will lay out my amateur predictamancy for those who wish to disagree:
10 quatloo says that no casters are involved in stopping the fire. That is, if you bet against me, and a caster is involved in putting out the Spacerock Inferno, you win. Bet concludes when the inferno does. If we don't find out when the inferno dies, or in the immediate aftermath (say, 5 relevant updates), no bet resolution, and not q are exchanged. Parson doesn't count as a caster for the purpose of this bet, obviously. Actually, I'll go ahead and say that you win if you bet against me and Parson does something magical to put out the fire.
As a separate bet, my 10 quatloo to your 20 says that Parson puts out the fire by ordering the city razed. That is, if you bet against me, you win 10 quatloo if the inferno is put out by methods other than the city being ordered razed. I win 20 q if the fire gets put out by the city being ordered razed (it doesn't necessarily have to be Parson who issues the order, though I'd be surprised if it was someone else).