News Flash to volcanologists: Given the magnitude of those past eruptions (or future ones of that magnitude and higher), there is NO preparing.......
Nuclear power plants powering indoor greenhouses and a lot of them, that’s about the only thing you could do to prepare for a major blow. Going to be considerably cooler with dim sunlight for years and years. Gorgeous sunsets or so I’ve read, though, so if you’re far enough away to survive, are able to keep warm and eat, at least there’s that.