On August 27th 1883 at 10:02 am a volcano on the island of Krakatoa in Indonesia erupted and generated the loudest noise ever recorded – so loud that it circled the earth at least five times!

The eruption was heard over 3,000 miles away. That’s like a sound created In San Francisco being heard in NYC.   It ruptured the ear-drums of  of the crew of a ship 40 miles from the eruption. A factory 100 miles from the eruption regeistered the noise as 172 decibels.  That is incredibly loud in its own right and downright amazing for being over 100 mikes away. For context, the threshold for pain is 130db and standing right next to a jet engine is 150db. Each 10db increase is a doubling of loudness. The top of the scale – from a physics perspective – is 194 decibels – higher than that and sound waves are so intense that a vacuum is created.  It is thought that the Krakatoa eruption created sound over the 194db threshold and that it created pockets of vacuum.

The noise from Krakatoa was recorded by changes in barometric pressure every 34 hours around the world for five days.  34 hours is the amount of time it takes for sound to travel around the planet.

So – it was really loud.