Cathryn;

The 22.1% is the odds on finding a 7+ quake in any 6 day period selected at random.

I found 60 supermoons associated with quakes. With 217 to pick from we would expect 48 hits. The z-binomial test tells us how likely it is to find 60 hits when we expect 48.

The answer is .03, meaning that in a very large test this would happen only 3% of the time, thus a significance of 97%

Roger