How to stop the cats from destroying the landing carpet...?

There's one landing that as a small step up from what is effectvely the first landing. The cats have taken to clawing the carpet on this particular area, effectively around the newel post.

Given the location I cna't put anything on it as it's right at the top of a set of stairs and don't want anyone to trip up, or down!

It may be that next year we replace all the carpets (again...), but I don't want to do that until we've figured out how to stop them.

I've tried putting a scrach wavey thing down for them, on two different flights of stairss, but they're not interested.

Help!