The methane is not mixed with oxygen when it's still in the rocket tank, so it can't all explode - most of it will just burn off.
It's still a big boom, but not anywhere close to what world occur with optional mixing.
The methane is not mixed with oxygen when it's still in the rocket tank, so it can't all explode - most of it will just burn off.
It's still a big boom, but not anywhere close to what world occur with optional mixing.
The side of the rocket failing appears to have allowed a lot of that mixing to occur after the initial fire.