Shanksville forest damage conflicts with official story

Here's an aerial photo taken on 9/12 that shows the aftermath of something exploding in the forest and causing major damage to a section of trees, including breaking off the tops of some, and also fire damage:

Let's piece together the official story to see what supposedly caused the damaged to the forest:

"[Wally Miller] explained how the cockpit broke off at impact, bouncing into a wooded area of about 60 acres. The resulting fireball scorched about eight acres of trees, he said.
The remainder of the plane burrowed deep into the ground, creating a long, narrow crater."

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UA93 Memorial Ambassador:

"Parts of the cockpit broke off and went back into the woods, but the rest of it went straight down and the ground came in around it, so the actual hole wasn't very large. When the FBI went in for parts, body parts and what not, 35 to 40 feet down in the ground."

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"According to investigators, the cockpit of the aircraft separated from the plane upon impact and flew into the trees, where it disintegrated."

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"A reporter for a Harrisburg public radio station, Lambert said Flight 93's impact hurled the plane's cockpit and first-class section onto the wooded land that has been in his family since 1930."

So Flight 93's cockpit section broke off from hitting the ground and was hurled into the woods where it exploded and disintegrated, causing severe damaged to the section of the forest adjacent to where UA93 supposedly crashed.

My question is,  

what's stored in a 757's cockpit to make it EXPLODE?

As mentioned in the official stories above, the remainder of the plane burrowed deep into the ground (see more reports saying most of UA93 buried here).

One of the landowners even says:

The plane "went in the ground so fast it didn’t have a chance to burn," says Jim [Svonavec].

This means only the 757's cockpit could have caused the forest damage, but I'm unaware of anything stored in the cockpit to make it explode like a bomb and cause fire damage.

So by that, the official story conflicts with the forest damage.

(I know the story about the cockpit breaking off while the rest of the plane burrowing underground is absurd in itself -- both that most of a 757 could burrow and if most could, that the cockpit and not the tailsection would be the section that managed *not* to burrow also -- and deserves its own thread, but I'm just using the official story to question the damaged forest.)