Here are rules for mudslides and avalanches, one of four new hazards presented in Treasure Hunter Adventures 6: Expeditions & Excavations.
These might be caused by an accumulation of snow that has piled up in a precarious way, or when heavy rain or an earthquake or volcanic eruption shakes loose dirt and rocks. However it happens, heroes caught in this predicament can take the following actions.
When this event occurs, there's no real choice but to be carried away by it.
After things have settled, the heroes must make Survival or Smarts in order to regain their orientation—that is, to figure out which direction is up.
With that in mind, the heroes must then make Athletics checks to dig out from it, with a -2 penalty for mud or dirt and rocks. This can be handled like a dramatic task (SWADE pages 122-3), with suffocation being the result if they are not successful.
Of course, other heroes can assist, as long as they were not themselves caught up in the hazard. In such a case, they should be handled as if they are working on their own dramatic task, with Notice checks to find the victim being the first necessary step.