[Barry_R]

Detonation itself won't line the ring gaps up.

But if you are running in detonation you will deform the piston - which will pinch the second ring as the land (the name for the upper and lower groove surfaces) folds up, locking it in place.

The damaged second ring segment will eventually cause the top ring land to deform and repeat the failure in a different fashion - by giving the upper ring's gap a place to "catch" in the dent - hence the line up.