The Krakatoa Eruption of 2012 was an event that occured during the 2012 apocalypse.
Presumably throughout the day of the 21st of December 2012, the island volcano Krakatoa erupted in Indonesia of the South Pacific due to the Earth's crust becoming unstable and lava forcing its way to the surface, due to the Earth's core's temperature being heated up so high. The volcano caused major damage to many areas of the island, triggering earthquakes and tidal waves that destroyed most of the islands in Indonesia, killing numerous people. Lava and volcanic ash engulfed the volcanic island and then some cities around Indonesia, rendering them uninhabitable.
The remains of the Krakatoa island were then swept by a megatsunami when the Worldwide Flooding occured, submerging it underwater.