The 1883 eruption of Krakatoa (now generally known as Krakatau) is one of the most famous and most deadly in recorded history. The volcano came to life in May of 1883 and was destroyed in a series of eruptions that occurred between the evening of August 26 and the morning of August 27 that year. Like a symphony roaring to a tumultuous finale, the volcano erupted four times during a span of about 5 hours in the morning of August 27. In the final cataclysmic explosion on that Monday morning, the mountain and the island it stood on were utterly shattered. Eleven cubic miles of rock and debris exploded into the atmosphere in an eruption so loud that it was heard nearly 5,000 km away on the island of Rodrigues on the other side of the Indian Ocean. The violence of the final explosion was exacerbated by the contact of sea water with a great quantity of hot magma. The shock waves, recorded by seismometers and barographs, circled the entire globe nearly four times and through the air seven times. Locally, the eruption forced barometric sensors completely off the charts. Over 36,000 people were killed–not from ash, or lava, or pyroclastic flows–but from tsunamis. Four of them–one with each eruption–were observed, with the final wave, which reached 120 metres high, tossing one ship over a mile and a half inland. Whole towns in Java and Sumatra were completely swept away. It is likely that the final tsunami was caused by the collapse of the caldera – the emptied magma chamber–beneath the ocean after the explosion. In the wake of the eruption, temperatures dropped globally over 1 degree Celsius over the next five years, and spectacular sunsets ensued (that may have possibly inspired Edvard Munch’s painting The Scream.)
Today, we are hearing news, once again, of destruction caused by tsunamis with their origins in volcanic activity on Krakatau. It only took less than fifty years for the volcano to rear up through the ocean again after it was destroyed in the 1883 eruption. The resulting cone is known as Anak Krakatau, the “Child of Krakatau,” and it has been steadily building up in the 135 years since the destruction of its parent. It appears that the tsunami was caused by a flank eruption (possibly underwater) and subsequent landslide/collapse at Anak Krakatau (this website has details and will be updated as more is known.) The volcano has been active for some time and this was not its largest recent eruption. Tsunami warning systems did not issue a warning for this particular tsunami because they are currently designed to monitor earthquakes only.
An interesting tangent: recent articles declaring 536 to have been “the worst year ever.” (See here and here for a couple of examples.) These articles point at an Icelandic volcanic eruption in 535 as the event that kicked things off. Previous studies have pointed at a North American volcano, but it is actually possible that Krakatau may have erupted in this timeframe–the Javanese Book of Kings notes an eruption in 416, but little other disruption, whereas there are significant gaps in the record around 535. Author Simon Winchester also notes a Chinese account from around that time noting a detonation heard to the south. Core studies done in Krakatau in 1999 note a major eruption at some point between 1 and 1200 AD.
Whatever the case, there is ample evidence provided just by looking at the geography of Krakatau to show that the volcano there has erupted violently on multiple occasions. Its situation in a particularly unstable portion of one of the most seismically active areas on Earth means that this is one volcano whose tantrums we must always take seriously.
Coda: I first heard of the 1883 eruption from William Pène du Bois’ children’s novel The Twenty-One Balloons, about an explorer in a balloon who crash-lands on Krakatoa. He discovers it is inhabited by 20 families who have become fabulously wealthy from a diamond mine on the island and have built elaborate homes based on letters of the alphabet that also double as restaurants. The inhabitants manage to escape with the explorer on a platform suspended beneath 21 balloons before the volcano erupts. It’s a tremendously fun read.
YouTube video of recent 2018 eruptions of Anak Krakatoa
Indonesia tsunami caused by collapse of volcano (from the Guardian )
Anak Krakatau: Volcanologist explains Indonesia eruption images (BBC)
Krakatoa Volcano: Facts About 1883 Eruption
Simon Winchester, Krakatoa: The Day the World Exploded, August 27, 1883. New York, 2003.