What geological feature shifted before the Spirhalite Islands resurfaced?

The tectonic plates shifted before the Spirhalite Islands resurfaced. In the game’s setting, the archipelago emerged from the sea after a tectonic shift, making plate movement the geological event tied to the islands’ return above water.

The Spirhalite Islands are a remote, previously uninhabited region where Splatoon Raiders takes place. Their isolation gives the adventure a distinct setting separate from familiar locations such as Inkopolis and Splatsville. The islands’ emergence also helps explain why the area is presented as mysterious and rich in unexplored ruins, treasure, and Salmonid activity.

“Coral reefs,” “volcanic vents,” and “ocean currents” are plausible geological or oceanographic terms, but they are not the named cause in the game’s backstory. The question asks which feature shifted, so “tectonic plates” is the canonical quiz answer: the underlying tectonic movement raised or reshaped the island region before it resurfaced.