The Hermosa earthquake was an event, a large natural disaster that struck the west coast of the planet Earth's North American continent in the year 2047.

As a result of the quake, a flood of water ended up submerging the city of Los Angeles under several meters of the Pacific Ocean. The city's ruins would end up providing the basis for a vital coral reef. Chakotay and Kathryn Janeway observed the city as a place that would one day be destroyed when they visited the past to the year 1996. (VOY episode: "Future's End")

The area would be renamed Los Angeles Island after the quake. (TOS novelization: The Motion Picture)