Krakatau volcano explosion. Computer artwork of the August 1883 explosion of the volcanic island Krakatau in the Sundra Strait, Indonesia. Seismic activity began in May 1883, and at 10:00am local time the island exploded. The sound from the massive eruption was heard over 4000 kilometres away and was probably the loudest sound in recorded history. Shock waves, detectable for 5 days, travelled 7 times round the Earth. Over 36,000 people were killed and 163 villages destroyed. Tsunamis followed, with waves of up to 40 metres high. Two-thirds of the 9-kilometre-long island was destroyed.