Possibilities for periodic non-fire runaway chemical reactions?

[Cogs13]

Basically, wondering what runaway chemical reactions alien "fire" fighters might fight on far away worlds. Also, this question is excluding grey goo and other biological/mechanical self replicating phenomena.



I'm really scratching my head on this one because I can't really think of something other than combustion as it occurs on earth. 

One key point is that in order for the reactions to periodically occur,

 A) the reactions need to peter out at somepoint, so they don't just convert the entire planet. 

B) the reactants and the initiation of their reactions need to re-occur or regenerate. I.e for runaway fires to occur, plant life needs to regrow to resupply the fuel. And then the lightning strike can occur. 

Maybe at the end of the day it would probably always be combustion or a combustion analogue. But if yall have any other thoughts to contribute that would be great.

[Drashner1]

Hm. Now I'm wondering if combustion can occur in the environments of either T'oulhome or Muuhhome. And what it might look like if it can or be replaced by if it can't.

Todd

[Cogs13]

I just considered runaway crystalization, but alas I don't really know how it would be "reset" or what candidate materials would be.

Another thought though is that there might be a matter of scale. Perhaps certain autocatalyzing reactions would be problematic for beings on the smaller side.

Also, I forgot about runaway gas/liquid releases, which might just be an atmospheric/hydrospheric hazard.

[stevebowers]

In a hydrogen atmosphere a release of oxygen, chlorine or fluorine would produce a flame. You'd need a reservoir of pretty pure gas, though.
Sodium and potassium burn in water, although on Earth the presence of oxygen dissolved in the water probably helps sustain the reaction.

[Drashner1]

What about digestion? Specifically, what about something like a locust/army ant swarm or maybe (to be more alien still) something like a high speed slime mold/the Blob that consumes organic matter across some large area but is also limited due to some combination of limited lifetime/running out of food/environmental limits?

During an outbreak it could consume organic matter in large quantities, but afterwards things could grow back - until the next time.

Another thought - on a world with more active tidal forces (moon of a gas giant perhaps) and a hotter core perhaps there would be more volcanic events and so mass destruction followed by renewal would happen more often.

Just some thoughts,

Todd

[stevebowers]

Planets orbiting red dwarfs closely can also have significant tidal heating. Cryovolcanism is another interesting source of high energy events. Even geysers on Earth have impressive eruptions on occasion.