We dont even know if there was an explosion. All we know is there is a fire on top of the platform. How does an underwater mine, using magnets, climb out of the water, then another 50 feet and jump on top of the platform?
I swear, some people would rather blame nefarious forces than try to find the truth.
So why can't you do this from a miniature submarine ~ sneak up on them, surface on one side the platform, toss a Molotov cocktail, and be gone in seconds.
Until we know the precise type of platform all things are possible.