Earthquake (1974) has everything that I love in a 70s disaster movie. If I wanted to explain the genre to someone I'd say go see Earthquake. Plus it has Chuck Heston. And it still looks cool. With no CGI!
My review: https://princeplanetmovies.blogspot.com/2023/07/earthquake-1974.html
@d4doome No CGI, but, IIRC, matte paintings and maybe some animation! And footage recycled into Battlestar Galactica 1980, where they added bonus Cylons.
@d4doome Another impressive disaster movie is San Francisco with Clark Gable, Jeanette MacDonald and Spencer Tracy. The 1906 SF earthquake sequence is amazing for a 1936 movie.