Avalanches

[Nicktacular]

I can't find anything in the books that says the cause of an avalanche. I mean is there any rules or should I just put in on a encounter list?

[Sian]

Frostburn?

[Nicktacular]

It doesn't say qnything about what causes avalanches it just says to refer to the dmg and the dmg just says what happens when one occurs not what causes it to occur

[Blackhawk748]

well REALLY loud noises doesnt, mythbusters actually proved that. A rockslide could. I believe the occur naturally when too much snow accumulates in one area and then some starts sliding.

[Red Fel]

Unless you plan to actually delve into the *ugh* science and physics behind avalanches, and in doing so determine precisely what causes them, I'd suggest following a fairly simple rule:

Avalanches happen because the DM says they do.

Sound like fiat? It is. Here's why. Natural disasters, at least those that aren't directed by explicit spells or abilities, happen. They do. If you're in a place where they're possible, they're possible. Obviously, there are exceptions; in the middle of a vast, flat desert, a rockslide is highly improbable; an avalanche of snow even moreso. But if you're in the hills, and there are loose stones around, and it would be reasonable and appropriate for rocks to fall... Rocks fall.

You say you've found rules for what happens when an avalanche occurs; good. My advice, however, is not to put it on an encounter list. An avalanche should be appropriate. I know I just said "natural disasters happen," which suggests that they should be random, but here's the thing - your players will not assume it was random. They'll assume it was caused by something. So don't make it random; make it appropriate. Are they in the mountains hunting dragons? Good a time as any. Are they pursuing a group of tunneling Underdark-dwellers? Great. But are they simply wandering through the countryside, and you roll "avalanche" on the random encounter table? They're going to waste an hour assuming they've been attacked. That dog will not hunt. Make it fit, make it thematic, make it more climactic than simply "Suddenly, rocks fall, everyone make a save."

Similarly, if you think it would be appropriate for the PCs to trigger one, do it. Rule of cool that bad boy. Wizard firing sonic attacks at the hillside? Not smart, bucko, make that save. And so forth.

Here's the bottom line. Natural disasters happen, and that basically makes them DM-discretionary features. But they shouldn't happen randomly. Whenever I consider using a random encounter table (disclaimer: not often), while constructing it, I examine the worst-case scenario: What happens if I roll this particular thing three or more times in a row? Orcs, orcs, orcs? Fine. Wolves, wolves, wolves? Sure. Drow, drow, drow? In the Underdark, perfectly understandable. Avalanche, avalanche, avalanche? That's just sadistic. In my mind, that wouldn't belong on an encounter table specifically because of that chance. Doing it once or twice is a good way to keep the players on their toes; having it occur randomly just feels cruel.

[GGambrel]

...Make it fit, make it thematic, make it more climactic than simply "Suddenly, rocks fall, everyone make a save."

This is a good point Red Fel.

Wikipedia seems to suggest most avalanches occur during storms as a result of snowfall: http://en.wikipedia.org/wiki/Avalanche.

I would suggest giving the players some subtle hints that an avalanche could be a possibility (large amounts of snow accumulation, dark clouds on the horizon, etc.) prior to a Knowledge (nature) or Survival check (perhaps rolled in secret, maybe DC 15 or 20) to indicate whether the PCs know such a risk exists. I think given player or PC knowledge, the option should be available to navigate around the risky area or wait for more favorable weather. If the warnings are not heeded, I would have there be maybe a 20%, 50%, or 80% chance of the avalanche occurring, depending on how heavily I hinted and how easy the skill check was (lower DC = higher likelihood).

Edit: I'd say put inclement weather on the encounter list (or perhaps its own weather list) and have the avalanche be a potential consequence of that weather.