Turns out, Poseidon had noticed before the rest of us and had gone out to play around in ash drifts. By the time the humans came out, he'd already made himself a nest next to the stable. He would have been in the river, and I'm sure he dipped in to wet his scales, if it hadn't become an opaque wash of dark gray and double in size from all the ash in it.
Other than that, everything seemed to be in one piece. The forest was still here, the hill was still here, even some of the wheat managed to keep peeking through the foot or two of ash like the last soldiers on a battlefield.
"Oh God, what happened?" asked Miur in a daze.