There ain't no studying "The Apocalypse" since it is supposed to be the end of the world. When we say "the end of the world" we mean the end of humanity. Humanity may well destroy itself, but the world, the planet, will continue without us as it has continued without many, many species that have come and gone.
A person who studies apocalypses is called an eschatologist.
Eschatologist.
a person that studies gems is called a gemologist.
A person who studies genealogies is a genealogist.
a person who studies people but not an psychologist
what do you call somebody who studies snails.
A person that studies animals is called a Zoologist.
A person who studies birds is called an ornithologist.
A person who studies birds is called an Ornitholoigst
A person who studies sociology is called a sociologist. They examine human behavior, relationships, and societies to understand how they function and interact.
The Apocalypse.
The study is paleontology so I think a person who studies it is a paleontologist.
A person who studies the aging process is called a gerontologist.