some kind of dimensional disturbance!
Art by Dave Gibbons, Doctor Who Weekly #2. Cover date 24 October 1979
The Doctor Who strip moves over to Marvel Comics UK and Doctor Who Weekly, and we get some gorgeous Dave Gibbons artwork to feast our eyes upon. The cause of the dimensional disturbance is likely the preceding events, in which the Doctor de materialises from the scene of an explosion.
Gibbons has constructed a wonderful black and white checker board on a perfectly skewed perspective, and appears to have an innate grasp of the TARDIS.