Thats extremely hard to do with volcano's in this version of DF, I managed to get 1 in a low desert, that was it. After like a hundred gens, and not using the PF settings. (I wasn't trying, just playing with the randomness of Toady's weighted maps). You could try something like:
[ELEVATION:100:400:1600:1600]
[ELEVATION_FREQUENCY:6:8:4:3:2:1]
[VOLCANISM:0:100:1200:1200]
[VOLCANISM_FREQUENCY:6:1:1:1:1:1]
[EROSION_CYCLE_COUNT:500] (or upto 1000), but erosion over 500 creates bad river canyons, 250 is the best compromise
[RIVER_MINS:800:400] <---- This is tricky but if you can get rivers to go over your volcano's, they'll flatten out.
If you set your elevation mins to 100, turn of your ocean edges to zero.
There's a link how to get volcanoes speckled everywhere for maximum volcanoes in low lying area's in the first post from cephalo on the project, he's kept it up to date.
http://www.bay12forums.com/smf/index.php?topic=57428.msg1424214#msg1424214You have to set your threshold sliders to 99-98% and set your cusp sliders far apart, and max out your noise sliders in volcanism. The above link describes it much better then I can.
[VOLCANO_MIN:200] be sure to set that to mucho high numbers like 200 if your doing the speckle thing with the volcanism map, if your doing it right it will look mostly green with 1 pixel red dots.
If you use PF for elevation maps and stuff you don't need to tweak weighted rangers or min/maxes.
If you do it on anything less then 257x257 map your going to have to figure out how to get the dots the right size, they need to be bigger.