Why do volcanic islands sink?

Most oceanic islands rise from the sea as a result of volcanic activity on the ocean floor. ... Sometimes, coral islands develop from reefs that form around the volcanic island. The original volcano may sink following movements in the Earth's crust, or because the sea level rose. read more

Again, no earthquake can sink an island. *No* earthquake is that strong - rock is tough, and the most that you'll get is a very large landslide. Volcanoes like Krakatoa, Tambora, and Santorini can really blow their tops - but even those explosions don't totally destroy the islands. Look at them. read more

Volcanic islands don't necessarily sink. For example, if we look at the Hawaiian Islands, we see that they are islands precisely because they are rising up above the surface thin plate and above the surface of the water. read more

Eventually the volcano stops erupting, settling into dormancy. No new rock is formed, and life takes hold as rock weathers into soil. Erosion gradually wears the rock into sand, while the volcano shrinks and sinks as the hot, buoyant rock cools from its younger days. Tahiti is an island formed by volcanic eruptions and shaped by rain. read more