From Pathfinder #177: Burning Tundra, which isn't enabled.

Methane Flue

HAZARD 8

Stealth +18 (expert) to hear hissing gas

Description Invisible but highly flammable natural gas has built up beneath the ground, where geological pressure can ignite it.

Disable DC 28 Survival to dig around the vent in a way that diffuses the fumes

AC 10

Flame Spurt

Trigger A creature moves within 5 feet of the flue

Effect A fiery geyser of flaming gas explodes from the ground. Creatures within 5 feet of the flue take 4d10 fire damage (DC 30 basic Reflex); creatures that fail the save also take 4d10 persistent fire damage.

Pathfinder #177: Burning TundraOGL