The loudest noise heard on earth

Krakatoa is a volcanic island in the Sunda Strait between Java and Sumatra in Indonesia. It has erupted repeatedly, massively and with disastrous consequences throughout recorded history. The best known eruption culminated in a series of massive explosions on August 26-27, 1883.
The 1883 eruption generated the loudest sound historically reported: the cataclysmic explosion was distinctly heard as far away as Perth in Australia (approx. 1930 miles or 3100 km), and the island of Rodrigues near Mauritius (approx. 3000 miles or 4800 km).
On no other occasion have sounds been perceived at such great distances (over 1/13th of the earth's surface).

It is difficult for the human being to imagine an apocalyptic noise as it is for him to imagine a definitive silence. Both experiences exist in theory only for the living since the set limits to life itself, though they may become unconscious goals toward which the aspirations of different societies are drawn.
[The Soundscape - R. Murray Schafer]

[What happened in the Krakatoa eruption in the 1800's? - via Volcano World]
[Discovery Channel: Explore the 1883 eruption]
[geology.sdsu.edu]