Denver Is Missing (1971) by D.F. Jones
Dennis Feltham Jones is famous for penning the Colossus trilogy of sci-fi books. The first, Colossus (1966) was made into the 1970 cult classic Colossus: The Forbin Project. Dr. Forbin builds a computer so powerful it makes nuclear war obsolete. But what neither Forbin nor anyone else suspects is that Colossus will gain consciousness and chart its own destiny as well as mankind’s.
In Denver Is Missing a young geologist out of San Francisco is on a deep sea exploratory drilling mission off the coast. His group is trying to gain information about the earths structure beneath the mantle. Unfortunately, their drilling pushes through into what turns out to be an unexpected phenomenon. This starts a chain of catastrophic geological events that release deadly gas into the atmosphere and tsunami-creating seismic activity.
The story primarily focuses, however, on two couples. The geologist and his girlfriend who have joined forces with a Brit sailor and his young plaything. The four of them choose to take to the sea to escape the chaos escalating in the cities of the West Coast. The majority of the book is taken up with their exciting adventures at sea as they try to sail away from a world gone mad.
The novel seems very influenced by the British school of 60's world-disaster novels written by, say, Ballard or John Christopher. The hero is a scientist who is often involved in a specialty that relates directly to the apocalypse. He has a dispassionate eye for the decay of the social destruction of civilization and there is a healthy dose of sexual politics thrown into the mix.
The ending of the book left me somewhat cold with it's idealism but, all in all, a good read and an excellent addition to the canon of post-apocalyptic fiction.