Bolides are just large bright meteors
There's nothing at all mysterious about bolides, which are just a larger, brighter version of the meteors, or shooting stars that can be seen any evening.
Why are we seeing a rash of big blue-green ones right now?
I'm going to speculate that the Earth is passing through an unknown debris field left by some anonymous comet, and just by chance, we're hitting a more dense portion of that debris field, hence the larger chunks, hence bolides.
As to the peculiar hue, very, very pretty, but just a consequence of chemistry.