The "fracture" being referred to is a weld that somehow failed. The gap you are seeing is because an enormous, heavy train travelling at 200km/h hit that fractu

The "fracture" being referred to is a weld that somehow failed. The gap you are seeing is because an enormous, heavy train travelling at 200km/h hit that fracture and the rear half of the train derailed, tearing up sleepers and kicking all manner of debris around including ballast and, in this case, parts of newly-fractured (and therefore weakened) track.