Lots of people have stated that the bomb could not have sunk the island. I agree due to the fact that the houses, swingset, and foot are still standing.
But I question the reasoning. I understand a bomb going off would probably flatten most of what we saw. But so would the force of the water covering the island as it sank. That is what bothers me. The bomb might have negated the electromagnetic energy, leaving a situation where the energy of the bomb is absorbed, leaving everything standing. Or, the bomb went pretty far down into the island, so perhaps if it went off somehow (I'm not a writer) and the energy was forced down and that made the island sink leaving the houses, swingset,and foot standing. But,again, as the island sinks a wall of water will rush over the land probably leaving nothing standing.
So, after all of that, I am pretty sure someone somehow "moves" the island into that position. If it disappears and reappears there, then maybe everything would still be standing.
I think I'm more confused then when I started.
Peace!