it would look bad.
VERY very bad.
Think Krakatoa times 1000
People who lived 20 miles away from Krakatoa went deaf from the initial blast shock wave.
It would be lights out for the US and most of western Canada. There has been a flurry of blogs & articles about the bison and antelope moving out of the park.
On the bright side, we wouldn't have to listen to The Won and his minions bloviating-on incessantly.
Having read Simon Winchesters book on Krakatoa, I don’t think it was the initial blast that was the big one. It took several days to build up to the final super blast that disappeared the entire mountain. It did cause a tidal wave that sent a tsunama up over 100 feet into a bay nearby. See the movie some time.