Krakatoa: the story of the world’s mightiest explosion
The biggest explosion the world has ever known (try to imagine: an estimated 13,000 times greater than the bomb that destroyed Hiroshima during WWII) happened on this day, August 27 1883, as eruptions of the Krakatoa volcano reached their peak.
To understand, the noise of the explosion was heard 3,000 miles (4,800km) away, five cubic miles (21 km^3) of rock and ash were projected 50 miles (80.5km) into the air, while 36.5m tsunamis were created and 36,000 people lost their lives.
The island of Krakatoa (originally Krakatau) featured three linked volcanic peaks on an area about 5km wide and 9km long in the Sunda Strait between Java and Sumatra.
Krakatoa exhibited its first stirrings in more than 200 years on May 20, 1883. when the passing German ship Elizabeth reported a cloud of ash and dust above the island. For the next two months, similar explosions would be witnessed by commercial liners and natives on nearby Java and Sumatra. With little to no idea of the impending catastrophe, the local inhabitants greeted the volcanic activity with festive excitement. Thunderous rumblings, incandescent clouds and natural fireworks lighting the night sky not only brought hordes of sightseers, but prompted people on nearby islands to hold festivals.
However, soon excitement turned to horror as Krakatoa literally blew itself apart, setting off a chain of natural disasters that would be felt around the world for years to come.
At 1.06pm on August 26 the first of a series of increasingly violent explosions occurred, and at 2pm a cloud of black ash rose 27km into the sky.
By the following morning Krakatoa’s three craters had been raging for more than 14 hours and then starting at 5.30am came a series of four monumental explosions. The third, at 10.02am, was so loud that it was heard nearly 3,200km away in Perth, Western Australia, and 4,800km away in Mauritius. This was the loudest noise the world had ever known, the equivalent of 200 megatons of TNT, 13,000 times the size of the bomb that destroyed Hiroshima.
The colossal series of explosions propelled ash to a height of 80km into the sky. Of the estimated 36,400 deaths, at least 31,000 were caused by tsunamis created when two-thirds of Krakatoa island was engulfed by water and literally disappeared.
Terrified people on nearby islands tried to flee when a tidal wave 36.5m high and moving at an estimated 480km per hour bore down upon them. As it hit the coast of Java it travelled about 24km inland, canceling the town of Anyer.
Then came the pyroclastic flows, a fluidised mixture of hot rock fragments, hot gases and entrapped air that moves at high speed, as much as 160km per hour, with temperatures reaching 600 to 700°C.
An estimated 4,500 people in their path were burned to death as the flows, stretching possibly 64km, roared over land and sea.
The eruptions diminished rapidly after the fourth massive explosion and by the morning of August 28, Krakatoa was silent.
However, two-thirds of the island had been destroyed, vanishing under the waves. Small eruptions, mostly of mud, continued until October.
Fine dust from the explosions drifted around the Earth, causing spectacular sunsets for a number of months but also forming an atmospheric veil that lowered global temperatures by several degrees.
Further volcanic activity over the years led to the creation of a new island at the same location. It is called Anak Krakatau, Indonesian for “Child of Krakatoa”, and it emerged in 1927 from the caldera left by the 1883 catastrophe.
Eruptions have continued there, most recently in each year from 2009 to 2012, and then a major event in December 2018. The eruption of Anak Krakatoa in 2018 caused a landslide and a tsunami with waves between 5 to 13m high. The water penetrated the coasts of Java and Sumatra as far as 330m, killng 427 people who were caught completely off guard.
In addition to Krakatoa, which is still active, Indonesia has another 130 active volcanoes, the most of any country in the world.