Several months later...The area is a mix of melted, re-solidified black glass and structures that have been chipped out of it, cracked and warped by scorchmarks and completely uninhabitable.
Steam and smoke hangs thickly in the air. A dwarf climbed the silt steps to the surface, looking round at the ruined remains of the outpost.
Imush was quick behind her, still shouting obscenities and insults. "You'll be outcast now, Wadedtrumpets! No one in the mountainhomes will accept you back now that you've gone and dumped all the supplies into the magma lake. Either you stick with us to clear out those imps or you're dead for sure!"
"No."
"What?" Imush got even redder, blinking smoke from his eyes. He didn't even see the blow that sent him stumbling back down the muddy slope. He scrambled to his feet. "CATTEN!"
She was turning the rusty valve as fast as possible, setting the chains and mechanisms into motion. The grates barring the tunnels below slammed down, sealing the dwarves in.
"You can't do this! Someone from the mountainhomes will come, and reveal your treachery!"
"There will be nothing to find." Catten said, and strode away to the small guard tower, which contained a short bauxite lever marked "DO NOT PULL".
Afterwards, there was a crunching sound of metal and the bubbling of magma. Catten began to laugh.
"You're all useless fools! Enjoy your last moments, Imush knife-ears!" The scent of charred flesh wafted from the grate.
"Er, what's going on?"
Catten turned, to notice a party of dwarves in travellers clothing standing behind her.
The dwarf looked at her, his beard arranged in double braids. Catten stared at them for a long minute before realising they hadn't seen the grim end of her outpost.
"You're migrants, right? For outpost Urdim Sákrith?"
"Aye. Catten Wadedtrumpets I presume? Our picks are yours."
"Don't get settled yet. We have a ways to travel."
The dwarves looked confused but didn't question. Catten unrolled a stretch of rotten parchment, from which she had inscribed "alternative plans" some months ago, on which was a map of a journey north.
"Gather what you can and load it into the wagon. We're leaving this rubble."
Catten dropped her outpost log into the bubbling grate.
(Yup, I'm continuing this.)