"On the Slopes of Vesuvius" is a very short story, a mini-shocker. Robert A. Heinlein sees the risks and potentialities in our potential futures so much more clearly than most of us. Vesuvius is the volcano in Roman Italy that famously exploded in A.D. 79, its eruption burying the nearby cities of Pompeii and Herculaneum in molten lava and suffocating ashfall.
James Gifford states the story's history concisely:
This short story, never published contemporaneously, was another try at 'world saving' in the vein of the articles Heinlein wrote in 1946, attempting to alert the citizens of the US to the dangers of a world wherein the atomic bomb is set loose. All of the articles failed; none were ever published prior to collection in Expanded Universe. ...
Robert A. Heinlein:
A Reader's Companion
Foreign policy comes home. "On the Slopes of Vesuvius" is a deft, unpleasantly salutary story.
Pompeii and Herculaneum could see Vesuvius out of their windows, but they didn't see it in their future.