At least not when we assume it did. Something isn't adding up in the intro of the episode. Kate is in a TREE! How did she get there? Some viewers reason: Jughead blasted her out into the Jungle and up a tree... But if there was enough time for the Blast to blow Kate up into a TREE, than there would have been ample time to instantly incinerate Juliet. Instead she lay under the beloved remains of Desmond's hatch, and to me it doesn't add up.
Seeing Kate in a TREE reminds me of a time when we saw Jack in the Pilot episode alone in the Jungle of sharp trees unharmed; or the time Desmond was running through the Jungle Butt-Naked after the implosion of the Hatch.. On all three of these occasions there was a Electro-Magnetic breach, but was there a H-Bomb explosion?
Laws of Physics would agree, there is absolutely no way Kate was blasted into a TREE and Julliet was left unharmed IF a H-Bomb exploded. Which by the way, is it not a little strange that the impact of the fall didn't explode the Bomb, but Juliets lifeless dying hits did the trick?? Really???
Here's what I think: As history was already written, Jack and crew caused the incident and dropped an H-Bomb into the Swan construction site, but it didn't explode (Faraday told them to bring the entire Jughead, but Sayid was wrong in thinking only part was needed to work). Dharma then continued on their construction of the Swan station, sealing the unexploded Jughead in cement (Which we have seen in the Hatch)... Yada Yada Yada Desmond will turn the failsafe key this time triggering the Jughead to explode, messing with timelines in more ways than we know......