Clashing Rocks, Cave-in, Collapse, Bury

The spell clashing rocks can result in a target being buried as if by a cave-in. A buried character can attempt to break free with a Strength check or wait to be dug out. However, I couldn't find any guidance in the game mastery rules that would indicate what penalties are applied for being buried. Does the debris entangle you, pin you, etc? Can you cast a spell with a Verbal component, or does the dirt fill your mouth when you try to speak? What about a spell with a Somatic, Material, or F/DF component? Are you being squeezed too much to move your hands with the required dexterity?

In my case, I cast this 9th level spell on an enemy wizard, and the DM had him Dimension Door out. I think his reasoning was that there is no Buried condition, and therefore no limitations on actions that a buried person can take.

My take is that there is a prescribed way to escape and other attempts (short of divine intervention type stuff) would ultimately fail.

The only semi-related literature I could find was in the Horror Adventures book. That describes the case of a person being buried alive in a coffin. It suggests that they could cast a spell while in the coffin if they spent a minute trying and succeeded at an Acrobatics roll. However, once out of the coffin, this example reverts back to making strength checks to escape.

Any insight you can provide would be greatly appreciated!

I ruled it thusly:
- You can cast Verbal-only spells, with a few conditions.
- You are too pinned down to use somatic components.
- If you happen to have proper M/F/DF in hand and manage to keep hold of them when you were buried (possibly a Strength check) you can use them. You cannot retrieve M/F/DF components once buried.
- If you aren't choking (and nothing indicates you are by default but the DM may add complications) you can cast spells but must make a Concentration check = the DC of the original spell to account for any unpleasant and awkward positions and discomfort from being buried alive.

What does being buried imply to you? You are stuck underground, you have no line of effect, your arms and legs are held in place by the weight of the earth above you (unless you can pass the strength check), you can only take mental actions, and you take 1d6 nonlethal damage per minute that becomes lethal once you are unconscious.

Cave-ins and collapsing tunnels are extremely dangerous. Not only do dungeon explorers face the danger of being crushed by tons of falling rock, but even if they survive they might be buried beneath a pile of rubble or cut off from the only known exit. A cave-in buries anyone in the middle of the collapsing area, and then sliding debris damages anyone in the periphery of the collapse. A typical corridor subject to a cave-in might have a bury zone with a 15-foot radius and a 10-foot-wide slide zone extending beyond the bury zone.

A weakened ceiling can be spotted with a DC 20 Knowledge (engineering) or DC 20 Craft (stonemasonry) check. Remember that Craft checks can be made untrained as Intelligence checks. A dwarf can make such a check if he simply passes within 10 feet of a weakened ceiling.

A weakened ceiling might collapse when subjected to a major impact or concussion. A character can cause a cave-in by destroying half the pillars holding up the ceiling.

Characters in the bury zone of a cave-in take 8d6 points of damage, or half that amount if they make a DC 15 Reflex save. They are subsequently buried. Characters in the slide zone take 3d6 points of damage, or no damage at all if they make a DC 15 Reflex save. Characters in the slide zone who fail their saves are buried.

Characters take 1d6 points of nonlethal damage per minute while buried. If such a character falls unconscious, he must make a DC 15 Constitution check each minute. If it fails, he takes 1d6 points of lethal damage each minute until freed or dead.

Characters who aren’t buried can dig out their friends. In 1 minute, using only her hands, a character can clear rocks and debris equal to five times her heavy load limit. The amount of loose stone that fills a 5-foot-by-5-foot area weighs 1 ton (2,000 pounds). Armed with an appropriate tool, such as a pick, crowbar, or shovel, a digger can clear loose stone twice as quickly as by hand. A buried character can attempt to free himself with a DC 25 Strength check.

Sometimes the rules are super literal and spell out exactly what a word means in official game terms, sometimes the game just expects you to understand basic real world definitions like "buried".

I agree there's not a lot of RAW as it's not about the PCs battling monsters or using feats...

environmental rules on d20PFSRD with suffocation rules.
on holding your breath and casting spells with that breath - Underwater thread, c2023

quickly transitioning to Advice...
RAW doesn't specifically talk about having breathing trouble or being pinned while buried so I wouldn't push that topic AND the underwater rules are quite generous for breathing. A GM can impose circumstance penalties in those situations.

You can see RAW gives characters a Rflx save to avoid damage and that is a big handwaive event. If a GM wanted to restrict somatic components I'd use that save. A buried caster could squiggle their way into their spell component pouch given time and gain access to material components or wands. I'd review the creature's current active/memorized spells as those could provide some space (particularly emergency force sphere, ablative barrier, liberating command, freedom of movement, and Wands).
If a GM wanted a creature to make some space while buried a STR check is indicated, a DC 25 frees the creature so it'd be less just to make some casting space.