The suggestions for events caused by the Blot are all passive "Tell the players this happened". Did anyone come up with Blot events that require some player interaction?
I don't see them as passive. Most of them give mechanical elements describing how they affect the PCs. Just make sure they happen at a time the PCs will notice. The magnetism happens when they're in combat, so they get the penalties to attack rolls and AC; the purple mist happens when they're casting a spell, so they get the Perception check to notice where it's going; the tidal wave happens when they're at the docks, so they can use all the listed skill checks; the falling rocks happen when they're outside, so they have to make the listed Reflex save (I upped the damage and the DC on this one, since it happened last and my PCs were higher level). All that's left are the sea gulls and the weather vanes; just have those happen when they're outside and in an area to notice what's going on.