Lucifer's Hammer

Lucifer's Hammer is a post-apocalyptic science fiction novel by Larry Niven and Jerry Pournelle, first published in 1977. It was nominated for the Hugo Award for Best Novel in 1978. The story details a cometary impact on Earth, an end to civilization, and the battle for the future. It encompasses the discovery of the comet, the LA social scene, and a cast of diverse characters whom fate seems to smile upon and allow to survive the massive cataclysm and the resulting tsunamis, plagues, famines and battles amongst scavengers and cannibals.

Synopsis from Open Library.