From what I can remember the volume and area light dont throw off heaps of actual light source, thats why its dark. Us ethe volume light in the lava and you could either use IBL or throw some spotlights around an play with their intensity etc. I did the tutorial on lighting but lost my notes...so thats all I can remember..LOL hope it has helped in some way though.
cheers bullet
bullet1968
"A Darkness at Sethanon", a book I aspire to model some of the charcters and scenes