Very soon.
Well since this is in The Fallen section of the forum, I suppose I should give the bible version of The Great Flood.
I am not a great fan of the bible, and I find the term Angel personally doesn't fit me and never use it to describe myself.
BUT ...
The story goes that The Watchers watched, and whilst watching fell in love.
Defection swiftly followed, and soon after that came weddings, wedding nights and offspring.
The offspring were monsters who reeked havok across the face of the good earth God had made, bringing devastation to every corner of the world and making God very angry.
God sent a messanger to Noah to ensure that some of the things he had created would survive, and then loosed a Great Flood which swept across the globe carrying with it God's vengeance. Once all traces of the evil had been destroyed the rain ceased and the flood water began to subside.
The Ark came to rest atop a mountain and the peaceful world that God had made began again.
And everyone lived happily ever after.......Well not really, but there it is.
Now one faction believes that all the Nephilim (babies of Angels and humans) were destroyed by the flood, never to be seen again. The Naughty Angels were punished and the humans went back to their lives, sullied and ruined but wiser and more violent!

And some believe that the giants and ogres in Faerie tales through the ceturies are really surviving Nephilim, who were spotted by accident by humans who could not comprehend what they were actually seeing. Indeed many think that the Sasquatch or 'big foot' is also a Nephilim living in hiding in our midst.
Me?
Well I think a huge Earthquake on the ocean floor caused a tidal wave of huge size and wiped out a good proportion of the dry areas of the earth, and everything that lived there too. Then receeding almost as quickly as it came and leaving death and chaos behind it.
But who am I to say you can't believe in a man in a big boat with a little white dove and the future of the whole human race in his hands?