If that gets your imagination going, I recommend reading up on the Toba catastrophe theory: https://en.wikipedia.org/wiki/Toba_catastrophe_theory.

In a similar vein:

http://www.nytimes.com/1983/12/20/science/homer-s-sea-wine-d...

It's obvious: Homer was talking about wine grapes, which can be blue.

Krakatoa that erupted in 1883 in Indonesia. This was pretty big as well. It was so loud that its explosion could be heard 3110 km away!

[0] https://en.wikipedia.org/wiki/1883_eruption_of_Krakatoa