The area around the abyss was sectioned off by something called an Illusion Frame.
Illusion Frames were usually used to deal with crime scenes left by Sequencers. As part of the ploy to keep the regular human population placated, the governments of the world had to find ways to hide the gruesome sights that would sometimes appear in the middle of their cities.
A great deal of funding and research led to the creation of Illusion Frames. Put in the least words possible, they hid large areas inside of illusory barriers and made them impossible to touch from the outside.
Anyone who crossed the border of the frame would find themselves turned around and sent in a different direction. Their mind wouldn't notice anything strange, nor would the people around them. It was a mixture of suggestion abilities and illusion abilities coalesced into a piece of technology rather than a person.
