Google "Isostatic Equalibrium." The Great Lakes region where you live is still slowly rising to achieve equalibrium after being relieved the weight of huge glaciers from the last ice age. Meanwhile the weight of the meltwater has been transferred to the Atlantic. That disequalibirum will, over time, affect tectonic plate boundaries.
Volcanic activity is caused by subduction of oceanic plates under continental plates. There are many forces affecting plate subduction, important among them the rate at which mid-oceanic ridges supply new plate material. But I think it's reasonable to investigate the relationship of isostatic movement at plate boundaries to volcanic activity.