At 10:02 AM on August 27th, 1883, a volcanic island in modern day Indonesia called Krakatoa erupted. The blast sent shockwaves across the ocean, triggering tsunamis that destroyed the coast of Java and Sumatra. The sound was so loud it was heard 3000 miles away.
As Aatish Bhatia notes in this recent article: “What we’re talking about here is like being in Boston and clearly hearing a noise coming from Dublin, Ireland.”
Barometric readings at the time clocked the sound pressure at 172 decibels ONE HUNDRED MILES AWAY from the island.
Here’s a handy reference:
Using a jackhammer – 100 decibels
Human threshold for pain – 130 dB
Standing next to a jet engine – 150 dB
And the scale is logarithmic - so a 10 dB increase doubles the loudness.
In 1883 just off the coast of Jakarta, a volcano on the tiny island of Krakatoa exploded. It had been building up for months, and on the morning of August 27th, the volcano erupted for the fourth time, blowing apart the entire island. It spewed out over twenty five cubic kilometres of ash, pumice, and rock, created tsunami waves over thirty metres high, and overall caused over 36,000 deaths. The eruption caused a shockwave of energy to tear around the globe seven times, and it was measured by barometers for a full five days afterwards. This peak explosion was about thirteen times larger than the Hiroshima bomb, and the sound it made was literally heard around the world: people heard it clearly as far flung as Perth, 3500 kilometres away in Australia, and even 5000 kilometres away, police officials mistook the eruption for “the distant roar of heavy guns.” The sound is estimated to have been around 180 decibels—as loud as a rifle shot at point blank range, and loud enough to instantly kill all hearing tissue in the human ear. It’s believed that Krakatoa’s eruption was one of the loudest sounds ever generated on Earth, rivalled only by the eruption of Mount Tambora in 1815, and the Tunguska event of 1908, when a meteroid or comet fragment exploded in the air above Russia. No wonder Krakatoa is considered the most dangerous volcano in human history.
Large, explosive volcanoes, like the 1883 eruption of Krakatoa, can temporarily alter global climate by injecting sulfurous gases into the high atmosphere. These aerosols cool Earth by slightly shading its surface, reflecting back to space some sunlight that would otherwise shine on it. The way volcanic aerosols reflect light produces vivid red sunsets.
The red skies in Edvard Munch’s famous 1893 painting The Scream are now thought to reflect the eerie twilights seen in Norway for months after Krakatoa’s eruption.
Erupting suddenly and violently on the 27th
August 1883, the volcanic island Krakatoa,
located between Java and Sumatra, threw out an estimated 17 cubic kilometres of
rock, ash, and pumice high into the atmosphere and triggered a deadly
pyroclastic flow of molten ash and gas that killed 1000 people on the coast
of Sumatra instantly. In the loudest bang ever-recorded in human history, the
explosion triggered a catastrophic tsunami that swept coastal towns and
villages and killed at least 36,000 people (though some estimates reach as high
as 120,000). Heard some 3000 miles away in Sri Lanka and Perth, with pressure
waves enough to travel round the world four times over, the explosion caused
global temperatures to fall 1.2° for the next five years, with the sun in the
area blacked out completely for three days.
Image credit: An 1888 lithograph of the 1883 eruption of Krakatoa. Image published as Plate 1 in The eruption of Krakatoa, and subsequent phenomena. Report of the Krakatoa Committee of the Royal Society (London, Trubner & Co., 1888). Lithograph via Parker & Coward, Britain. Public domain via Wikimedia
The volcanic island of Krakatoa, located between the islands of Java and Sumatra, lay dormant for at least two centuries, before a passing European ship reported seeing enormous clouds of ash and dust rising from the area in May of 1883. Over the following months, volcanic activity in the region intensified, before reaching an apex on August 26th and 27th of that same year.
Four enormous explosions took place on August 27th, resulting in the destruction of at least two-thirds of the island. The sound produced by the eruption was so loud that it could be heard 3,000 miles away (on the island of Rodrigues in the Indian Ocean, the sound was initially thought to be the “roar of heavy guns”). The black clouds of ash spewed into the air by the volcano rose fifty miles high. Each of these colossal explosions was accompanied by tsunamis, which single-handedly killed off a large fraction of the (official) death toll, which was estimated at 36,000. Pyroclastic flow reached neighboring islands (including Sumatra) and wiped out vegetation, villages, and people. For months around the world, sunsets glowed unusually brilliant colors as a result of the gases emitted by the volcano; one British poet, Gerard Manley Hopkins, described this phenomenon:
…more like inflamed flesh than the lucid reds of ordinary sunsets… it bathes the whole sky, it is mistaken for the reflection of a great fire.
It is also sometimes theorized that Edvard Munch’sThe Screamalso depicts the after-effects of Krakatoa, similar as to what was described by Hopkins.
In modern terms, the eruption of Krakatoa is estimated to have had a yield of around 200 megatons; to put things into perspective, the “Fat Man” device detonated over Nagasaki had a yield of 21 kilotons, while Tsar Bomba, the most powerful nuclear weapon ever detonated, had a yield of 50 megatons.