Well,,,, we finally know what started the big old mud volcano in Java. There was a very high spike of pressure, probably gas and water, that eroded out the drill stem, and the rest is history.
Although they had put in some sort of blowout preventer, it was not enough. The question is whether anything would have been enough, or perhaps they just should not have been drilling there. I can't see that anyone had foreseen something like this happening. As for the actual mud volcano, it has blown out like a giant zit, and is now cratering.