Tactical coordination. It's tempting to have everyone run around, digging as fast as possible, but that does increase the risk of instability. Ideally, we want to move as little as possible, to reduce the risk anything becomes unstable and falls further. Search for people closest to the the surface of the collapse first, try not to have too many people climb the rubble.

[ A mage might be useful, to help carefully levitate pieces, but he's not sure how many people in their party have that form of ability. Pure strength will work. ]