Fault line

According to the Tenth Doctor, the ghosts were "bleeding" through the fault lines, crossing from their world across the Void and into N-Space. (TV: Army of Ghosts)

In 2015, when a froze all planes in the skies across the globe, Clara Oswald speculated with UNIT that they could be used in an attack by targeting fault lines to cause earthquakes or tsunamis. (TV: The Magician's Apprentice)