When I watched both trailers I was intrigued. In Locke's trailer I noticed that the Chief had a large hole in his armour and the armour on his left shoulder was practically gone. Locke either had some big firepower with him at some stage or something happened that may have also destroyed the area they are in. In Chief's trailer, I thought Locke has sustained a lot more damage. Locke also has a large hole in his armour but sparks are flying from his back. The Chief had to also have big firepower at some stage as well. What I've got from this is that maybe the War Sphinx seen in the Halo 5 trailer is responsible for the destruction.