Krakatoa- a Theme in Terry Pratchett's novel

It is set in an alternate 19th century, where a tsunami of Krakatoa proportions lays waste the oceans and leaves a native boy, Mau, alone on a devastated island with Daphne, a prim mid-Victorian girl marooned by the same wave. Their shy and difficult relationship becomes the centre of their drive to save the storm-washed refugees who reach the island, in the course of which they have to fight off attackers of all kinds to find the secret hidden in the island’s traditions, that almost literally turns the world upside down.

Krakatoa 
The 1883 eruption of Krakatoa in the Dutch East Indies (now Indonesia) began in the afternoon of August 26, 1883 (with origins as early as May of that year) and culminated with several destructive eruptions of the remaining caldera. On August 27, two thirds of Krakatoa collapsed in a chain of titanic explosions, destroying most of the island and its surrounding archipelago. 
This event had inspired Pratchett to base his story on the tsunami caused by Krakatoa.