Krakatoa -- In the Indonesia Island Arc sits Krakatoa, remembered for its massive eruption on August 27, 1883 that killed 36,000 people and was heard 2,800 miles away (it is considered the loudest sound in modern history). The Indonesian Island Arc is also home to Mt. Tambora, whose eruption on April 10, 1815 was the largest in major history, being calculated as a 7 on the Volcanic Explosion Index (VEI).