The Flight 93 Crash, Revisited, Again

In this post, I talked about how strange it was that flight 93 could plow deeply into the earth such that the plane was not even visible, but still explode violently, spewing debris hundreds of feet back in the direction from which the plane supposedly came.

Supposedly the plane could penetrate so deeply into the ground (15-25 feet) because the earth was soft dirt filled in over an old strip mine. The plane in fact plowed so deeply into the ground such that you could not even see recognizeable airplane pieces at the crash site. Fine.

(This information is from Jere Longman's book on UA Flight 93-- "Among the Heroes", which portrays the official flight 93 story in more detail than one is likely to find anywhere else.)

Here's the question. Wouldn't the soft earth act much like water would to dampen any explosion?

Let's put it another way-- if a plane crashed nose first into deep water, would we expect the plane to explode?

If someone could explain how the plane could burrow into the ground AND explode massively, I'd appreciate it.