I don't know what caused this crash but that's what the end of a stall spin looks like in a sailplane. Looks like this guy lived because he was lucky and because his sailplane's cockpit was strengthened beyond what is normal. (That wing hitting first may not have hurt either.)
One of my very good friends died years ago exactly like that. First flight in a one of a kind high performance homebuilt called an HP-18. It had a side stick when nothing else did, a T-tail and a wicked over the the top spin entry. A short restricted grass field, pilot with more money than skill, PIO on tow and an early release. Add a slow/low uncoordinated turn back to the field, an over the top entry and in just one short rotation he was dead.
Those are fantastic pictures but they damn sure give me the willies