Thanks for uploading your world jei!
I've never seen a volcano tile right next to a river.
That's my next embark. 
Could you possibly upload your worldgen parameters for that world, I tried exporting them from
your save and reggening, but for some reason, it always stops at "running rivers" and rejects the region.
There's one in there that's right next to a sea too, though I didn't point it out especially..
Can't you export the parameters from the legends mode into a file with [p]? I just gen the world and ignore all rejects.
Also, I'm glad that someone else likes having their rivers next to volcanos too!

I'm now trying to generate one in
2x2 or 3x3 size with Major river, a volcano and terrifying or joyous wilds areas. (I have yet to really experience joyous wilds
and one test embark assured me that it's a must have experience too.) Maybe with seashore if I'm that lucky. So far no
luck getting them on such a small area though.
I'm wondering as well if there's not a better way to do all this worldgenerating. (Windows apparently has some cheat
tools available for such things? Too bad I don't have Windows..) Toady should really make sure that by default such
embark sites are available in every worldgen. Not to mention an obscene Adamantine spine/spire -site too!
Also, I once had an embark site (river and volcanoe) with a goblin tower right in the area. Boy that was fun,
but that was in 40d and I don't have the saves or parameters anymore. I also wish Toady would let embark take
place in the tower/town areas like it used to be possible. Nothing like panickly digging your team into the ground
and barricading yourself in for years until you emerge as a threat to the tower..
Also an idea comes to mind that Areas could develop or change their alignment as time passes. Maybe "a Dark Moon
rises" that will turn an area into Terrifying and then go back to Joyous Wilds as it sets during a few years of game.
This could be a convenient plot excuse to turn the same area in one fortress game between alignments and change
the fauna and plants that grow during the years. It would make Fortress mode tons more fun if you could influence
the area alignment within the game.