My back door looks remarkably similar to your hallway. In my case the handiwork was done by S when she went into heat for the first time. But S got quite a bit farther in her digging than your cat. Apparently she decided it was a worthwhile project to dig her way through the backdoor into the back yard so she could go on the prowl for a mate. If I hadn't had her spayed I fully believe she would have succeeded. Now she spends her time working on other home projects including "resurfacing" upholstered chairs and sofas.