Wow thats some seriously upset colonists. Dropping garrison battalions on the planet should help to restore order but I think its going to take a long time.
In the bottom left corner of that tab are two lines, one for how much defence the planet wants and the second for how much there is, is there a big gap in that one? If so building PDCs on the planet will probably help a lot as well.
It's a difference of about 70, which is a lot less than the difference on Earth which is about
1,100 1,437 (does Earth not get political unrest, or is that a settable option for games?).
So. . . how do I go about building PDCs?