What exactly was, or happened in the Doom of Valyria?
I'm nearing the end of the ASOIAF books and despite countless references, I'm still not clear on what exactly the doom of valyria was. If I recall correctly, there have been many different mentions of what appears to be natural disasters. For example:
In A Dance with Dragons (Chapter 33):-
Tyrion is quoted as thinking..
An empire built on blood and fire. The Valyrians reaped the seed they had sown.
The implication being that Fire was the Doom of Valyria.
Fire is mentioned often, with clear references to the 'Fourteen Flames' which I believe to be a chain of volcanoes.
Many other seemingly natural disasters are described, these including earthquakes and a tsunami(?).
This makes me wonder, are all these events chained? As in, related or even caused by each other? Was the Doom of Valyria a completely natural event?
Did magic play a part, in any form? I know from references in the books, that magic was very prevalent in Valyria.
As stated I'm nearing the end of the books now, so any 'Spoilers' which answer my question or relevant questions are very welcome.