The story
From ice + shove, in reference to ice being shoved onto shore, and shoving items on shore further inland.
Etymology from Wiktionary, CC BY-SA 4.0.
ice shove
Today it means: A phenomenon which occurs at the interface of land and water, when partially frozen-over bodies of water with broken ice encounter a constant wind that blows onto shore, blowing the pieces of ice onto shore, which pile up and drive further inland, potentially crushing shoreside buildings or pushing them off their foundations. Full definition →