I'm afraid i cant be very helpful here but when i was much younger i watched an episode of a tv series which i remember being Sliders but cant seem to find any episode of that show with this description.
The part i remember is the end of an episode where there is a preview of the next episode. The preview involved the protagonists (cant remember anything about them) finding themselves in a city where the surround horizon contained a wave larger than all of the buildings in the city which was closing in upon them. I remember the city being empty apart from just them.
I know this isn't much to go on, I remembered this for some reason the other day and was hoping to watch the full episode but browsing the descriptions for the episodes of sliders (which i was sure it was) i couldn't find anything of that description.