I have to say you've done a nice job with the fire. The smoke is really subtle, yet it's actually how smoke looks in real life. Nice job going against any "smoke is GREY!" pre-conceptions.
It's a very small crit, but something about the volcano bothers me. I think the lava erupting out of the top should either take a parabola shape, if you're going for a prolonged-exposure effect, or show individual lava pieces, as it is in real life (
http://www.youtube.com/watch?v=IiEw1p5BaSU). But if you go for prolonged-exposure, you'll have to make the fire prolonged-exposure too.