"Horror is not a genre, like the mystery or science fiction or the western. It is not a kind of fiction, meant to be confined to the ghetto of a special shelf in libraries or bookstores. Horror is an emotion."
The removal of safety can be of a more moderate nature. One of the most effect invocations of horror is the façade of safety in the beginning of the tale and the removal of that safety after the author/creator has established how benign and peaceful a particular situation is at first. Some incredibly well done examples of this are THE FOG (film) by John Carpenter, ‘
The most cringe-inducing moment in King’s ‘Salem’s Lot is when grave digger Mike Ryerson is staying in Matt Burke’s house as a guest overnight, Matt Burke hears things amiss in the darkness.
“Softly yet clearly in the silent house the words came, spoken in Mike Ryerson’s voice, spoken in the dead accents of sleep:
‘Yes. Come in.’
Matt’s breath stopped, then whistled out in soundless scream. He felt faint with fear. His belly seemed to have turned to lead. His testicles had drawn up. What in God’s name had been invited into his house?”
The horror here is quite clear. The relative safety of the character’s surroundings (his house) has been violated by an outside force. The removal of safety sends any of us—all of us—into a disjointed semi-panic. Our world is not right, unless there’s a modicum of safety involved in it. Strip away that safety and you can induce some serious gooseflesh.