Good point. Also worth noting that that was comparatively mild; according to Wikipedia, St. Helens ejected a little more than a cubic mile of material, whereas Mt. Mazama is estimated to have ejected about 27 cubic miles of material. It's hard to imagine that kind of explosion.
Mt. Mazama seems to have been a bit of an outlier, though:
> The United States Geological Survey has referred to the 7,700 years ago Mazama eruption as the largest explosive eruption within the Cascades in the past million years, and one of the largest eruptions during the Holocene epoch.
Seems kind of improbable that the biggest anything happened in the most recent 0.77% of the observed time interval, which makes me wonder if there may have been others we just don't know about. Improbable events do happen though, so maybe it's just dumb luck (if we want to call it that) that we had such an event within relatively recent history.
> Seems kind of improbable that the biggest anything happened in the most recent 0.77% of the observed time interval,
The biggest has to happen sometime, and whenever it does will be an improbable time for it to have occurred if the probability is uniform and the resolution of time tracked is high relative to the total interval.
