I have somewhere in a box of old photos, a pic of a C172 that looks almost the same (bar the bit the fireys cut).
The aircraft was operating at low level and stalled, clipping a tree then impacting at about 45 deg nose down. The torn fuselage around the rear window and other damage looks familiar..
The U/C mount has a bolt through it that snaps on high forward (or backwards !) impact that allows the leg to rotate up or back.
Guess the ATSB will work out what happened..
This chap is very lucky, the one i helped recover was not.
PI