Red glow over Pacific Ocean. 
Credits: Author Flying Dutchman/Pilot JPC van Heijst.

Then, very far in the distance ahead of us, just over the horizon an
 intense light flash shot up from the ground. It looked like a lightning
bolt, but way more intense and directed vertically up in the air. I have
never seen anything like this, and there were no flashes before or after
this single explosion of light.

Since there were no thunderstorms on our route or weather-radar, we
kept a close lookout for possible storms that might be hiding from our
radar and might cause some problems later on.

I decided to try and take some pictures of the night sky and the strange
green glow that was all over the Northern Hemisphere. I think it was
sort of a Northern Lights but it was much more dispersed, never seen
anything like this before either.

About 20 minutes later in flight I noticed a deep red/orange glow
appearing ahead of us, and this was a bit strange since there was
supposed to be nothing but endless ocean below us for hundreds of
miles around us.

A distant city or group of typical Asian squid-fishing-boats would not
make sense in this area, apart from the fact that the lights we saw were
much larger in size and glowed red/orange, instead of the normal
yellow and white that cities or ships would produce.

The closer we got, the more intense the glow became, illuminating the
clouds and sky below us in a scary orange glow. In a part of the world
where there was supposed to be nothing but water.

The only cause of this red glow that we could think of, was the
explosion of a huge volcano just underneath the surface of the ocean,
about 30 minutes before we overflew that exact position.