So what could possibly create such an earth-shatteringly loud bang that was heard 3000 miles away?
On 27 August 1883, the Earth made the loudest noise in known history. The volcanic eruption in Krakatoa Island (Indonesia) annihilated the whole island, sent smoke up almost 80 kilometres into the air and killed 36,000 people in few hours. It was so loud that the sound waves turned into a shock wave (defined below) and shattered the eardrums of sailors 40 miles away.
“A sonic boom is the sound associated with the shock waves created by an object traveling through the air faster than the speed of sound. Sonic booms generate enormous amounts of sound energy, sounding much like an explosion. When a source exceeds the 194 db sound mark the energy stops moving through the air and starts pushing the air outward with an expanding vacuum.“
The Krakatoa explosion registered 172 decibels at 100 miles from the source observed by Batavia gasworks barometer. This is so astonishingly loud, that it’s inching up against the limits of what we mean by “sound”. Here is a decibel level chart to put these numbers into perspective.
Closer to Krakatoa, the sound was well over the 194 dB limit and created the shock waves. It was heard all the way in Australia and even as far away as Rodrigues Island, 3,000 miles away. Yes, 3000 miles away! To better understand, if you are living in Boston or Newyork, imagine you hear an eruption from Europe or California.
One final mesmerizing fact is the sound waves created by Krakatoa circled the Earth 3.5 times for the next few days.
Below is a video of an eruption from Papua New Guinea which is probably thousand times smaller than Krakatoa but still gives the experience of a shock wave.
Now imagine you hear this shotgun like sound from an eruption 3000 miles away, that is a mind blown!