youthquake
A noticeable shift in society or culture in response to the activities or tastes of younger members of the culture.
informal
Britain produced many of the first temblors of the youthquake. There were the elegantly dressed but often vicious Teddy boys of the late 1950s. There were the gentler Mods and the tough leather-jacketed, working-class rockers in the '60s.
Where it comes from
From youth + quake, by analogy with earthquake. Coined by American magazine editor Diana Vreeland in 1965.
Adapted from the Wiktionary entry youthquake (CC BY-SA 4.0).