I don't believe there is an alternative to allowing nature to take its cataclysmic course. There would almost surely be precursor signs building to a major eruption. I suspect there would be a huge migration to the north and south. Mexican illegal aliens might even stop coming into the US for awhile.
There have been about 30 Pinatubo scale-eruptions at Yellowstone in the past 600 thousand years as well. Chances are much more likely we'd see one of those lesser blowups in our lifetimes.
When, where and how powerful was the Pinatubo eruption?