49 Fun Facts About Krakatoa

Krakatoa lies in a strait between which two Indonesian islands?

Java and Sumatra. The strait between them is a busy sea lane, which is why so many of the first reports of the 1883 eruption came from the decks of passing ships.

News of Krakatoa's 1883 eruption reached the world within days thanks to which new network?

Undersea telegraph cables. The newly laid worldwide network flashed out the news at once, which is why Krakatoa is often called the first catastrophe the whole world followed as it happened.

Krakatoa rates a 6 on the Volcanic Explosivity Index, about ten times the size of which 1980 eruption rated a 5?

Mount St. Helens. Each step up the index means roughly ten times more erupted material, so the blast that flattened forests across Washington State was about a tenth of Krakatoa's size.

Krakatoa's climactic blast is put at about 200 megatons, four times the yield of which nuclear device?

Tsar Bomba. The largest device ever detonated, the 1961 Soviet test yielded about 50 megatons, and only because its builders had halved its design to limit the fallout.

Krakatoa's biggest blast was heard thousands of kilometres away on Rodrigues, an island belonging to which Indian Ocean nation?

Mauritius. Rodrigues lies some 3,000 miles from the volcano, so the sound its people heard had already been travelling for about four hours.

Krakatoa's official toll was 36,417 dead, yet which Indonesian eruption of 1815 is the only modern one rated bigger?

Tambora. Its 1815 blast is the only modern eruption to rate a 7 on the explosivity index, and it chilled the globe so badly that 1816 became the 'year without a summer'.

The 1883 collapse that swallowed two-thirds of Krakatoa island left what kind of sea-filled volcanic basin?

A caldera. Geologists think most of the island was not blown sky-high but sank into its own emptied magma chamber, leaving only the southern third above the waves.

What does Anak Krakatau, the name of the island that began to rise from the sea at Krakatoa in 1927, mean?

Child of Krakatoa. Steam and debris began spewing from the sea there in late 1927, forty-four years after the catastrophe, and within months the rim of a new cone broke the surface.

No earthquake caused the 2018 tsunami that killed over 400 people; what did Anak Krakatau do instead?

Its flank slid into the sea. More than two-thirds of the cone's volume went at night, and the wave struck without warning because Indonesia's alarms were built for earthquakes.

Krakatoa's first explosions in May 1883 were heard 160 km away in Batavia, the city now known as what?

Jakarta. The rumbling died down within days and the volcano seemed to settle, three months before the catastrophe that killed tens of thousands.

The jungle that reclaimed a coast emptied by Krakatoa's tsunamis now shelters the last wild population of which animal?

Javan rhinoceros. The villages wiped out there in 1883 were never fully rebuilt, forest took their place, and the peninsula became the species' last stronghold.

A 1968 disaster film famously put Krakatoa on the wrong side of Java; which side is it really on?

West. The volcano lies in the strait at that end of Java, yet the Cinerama epic went out as 'Krakatoa, East of Java' and still earned an Oscar nomination for its special effects.

Krakatoa and the chain of volcanoes around it sit above the sinking edge of which tectonic plate?

Indo-Australian Plate. It grinds north and dives beneath the two islands, and the rock it drags down melts and rises to feed the chain of volcanoes above.

Before 1883, which was the tallest of Krakatoa's three volcanic cones?

Rakata. The southern cone was also the only one to outlast 1883, sliced open so that a sheer cliff now faces the water where the rest of the island used to be.

Krakatoa's 1883 outburst is classed as Plinian, a type named after the Roman who described which eruption?

Vesuvius. Pliny the Younger watched its towering column of ash in AD 79 and described it in a letter about his uncle's death, giving volcanologists their word for such eruptions.

Which European country ruled the East Indies when Krakatoa erupted, and so compiled the official death toll?

Netherlands. Its colonial officials counted the dead and the 165 villages destroyed, and the governor-general ordered a full scientific account of the eruption.

Crews of which two ships stopped at Krakatoa in 1780 on their way home after Captain Cook's death?

Resolution and Discovery. Sailing home after Cook was killed in Hawaii, their crews found a friendly village, fresh water and a hot spring on what was then a quiet, inhabited island.

Krakatoa's biggest explosion was heard in which Australian state capital, more than 3,000 km from the volcano?

Perth. Oddly, blasts heard that far away were muffled or even inaudible near the volcano itself, perhaps because the sound was thrown upward and came back down far off.

When a French expedition landed on Krakatoa in May 1884, what was the only living thing it found?

A spider. Its finder wrote of a solitary pioneer already spinning its web, while every other trace of life lay buried under a thick layer of sterile ash.

Viral footage of the 2018 Anak Krakatau tsunami showed the wave crashing into what at a beach resort?

A rock band on stage. The Indonesian group Seventeen was mid-concert at Tanjung Lesung when the wave smashed into the tent and swept the stage away, killing its bassist and road manager among others.

Krakatoa shares its 1991 UNESCO World Heritage listing with which Indonesian national park?

Ujung Kulon. The volcano's islands earned their place as a natural laboratory, where scientists have watched plants and animals recolonise sterilised rock since the 1880s.

When Krakatoa first stirred in May 1883, three months before the catastrophe, how did many locals respond?

With sightseeing trips. Steamers were chartered to view the eruption and islanders held festivals under the natural fireworks, until the explosions of late August ended the party.

The four great explosions that destroyed Krakatoa island in August 1883 all came within roughly what span?

A single morning. Four blasts between dawn and mid-morning on 27 August finished what three months of lesser eruptions had begun, and the island's northern two-thirds were gone by lunchtime.

What did listeners thousands of kilometres away take the sound of Krakatoa's biggest explosion for?

Distant gunfire. After crossing up to 3,000 miles the blast had faded to dull booms like far-off artillery, yet it is still reckoned the loudest sound in recorded history.

Which instruments around the world recorded Krakatoa's air wave passing again and again for five days?

Barographs. These recording barometers caught the pulse as many as seven times, strong enough to be traced on both its outward and its returning trips around the planet.

What did Krakatoa's biggest blast do to many of the crew of a British ship some 64 km away?

Burst their eardrums. More than half the crew of the Norham Castle were injured that way, by a pressure pulse that also drove a gasworks gauge 160 km away off the top of its scale.

Where did Krakatoa's tsunami dump the steamship Berouw?

About a mile inland. All 28 of her crew were killed, by waves that reached some 120 feet and wiped out 165 coastal villages.

How did the steamship Loudon survive the tsunami that erased the port of Telok Betong?

By turning into the wave. Captain Lindemann swung the bow to meet it, the ship climbed over the crest, and those aboard looked back to find the town they had been anchored off gone.

What happened to the roughly 3,000 people of Sebesi, an island close to Krakatoa, in 1883?

Not one survived. The waves stripped Sebesi of its trees and houses and carried its people out to sea, leaving no sign that anyone had lived there.

Thousands of Krakatoa's victims were burned rather than drowned; what crossed 40 km of sea to reach them?

Pyroclastic flows. The avalanches of hot gas and ash skimmed across the strait on a cushion of steam and scorched villages on the far shore.

Which British scientific body published an exhaustive report on the Krakatoa eruption in 1888?

The Royal Society. Its Krakatoa Committee, with G. J. Symons as editor, gathered accounts of the strange skies seen around the world for months after the eruption.

For up to a year after Krakatoa erupted, rafts of what washed up on Africa's east coast bearing human skeletons?

Pumice. Huge fields of the floating rock drifted across the Indian Ocean for months, and near the volcano it lay thick enough to bring ships to a halt.

Which gas, blasted into the stratosphere by Krakatoa, dimmed the sun and cooled the planet's weather?

Sulfur dioxide. High winds spread it round the globe as a haze of sulfuric acid that bounced sunlight back into space, until it finally fell out of the sky as acid rain.

Which famous painting's sky have astronomers linked to the afterglow of Krakatoa's eruption?

The Scream. Munch wrote of a sunset walk when the sky turned blood red, and astronomers argue he was recalling the Krakatoa twilights seen over Norway in the winter of 1883-84, though art historians have dated the walk years later.

In late 1883 Krakatoa's lurid sunsets fooled New Yorkers into calling out what?

The fire brigade. Fine volcanic dust had spread around the world by November, and the evening sky flamed so red after sunset that many thought a great fire was burning.

What were the 'Krakatoa easterlies', the high winds that carried the volcano's dust round the tropics, later found to do?

Reverse direction. The dust revealed an easterly wind high over the equator, and later soundings showed it trading places with one blowing the other way every year or so, a cycle now called the quasi-biennial oscillation.

What colour did the moon appear in many parts of the world after Krakatoa's eruption?

Blue. Some of the ash particles were about a micron across, just the right size to scatter red light, so moonlight came through blue and sometimes green.

Which sky phenomenon has no confirmed record before 1885, when watchers of Krakatoa's sunsets first described it?

Noctilucent clouds. The silvery wisps shine long after dusk because they float about 80 km up, so high that they still catch sunlight when the ground below is dark.

Which South Pacific volcano's 2022 eruption sent out a pressure wave rivalled in recent centuries only by Krakatoa's?

Hunga Tonga. Its January 2022 blast was heard as far away as Alaska, and its shock wave was tracked around the globe by weather stations, as Krakatoa's had been in 1883.

Which 1947 children's novel imagines Krakatoa as a diamond-rich island with a utopian society?

The Twenty-One Balloons. William Pène du Bois's hero crash-lands on the island just before it blows up and escapes with its families on a platform held aloft by balloons; it won the 1948 Newbery Medal.

Which writer's 2003 book is subtitled 'The Day the World Exploded: August 27, 1883'?

Simon Winchester. He argues that the eruption, reported around the planet within days, marks the birth of an age of global awareness.

Krakatoa's gases spread through the stratosphere, but its ash is estimated to have shot some 80 km up, into which higher layer?

Mesosphere. Lofted that far above the weather, the finest dust stayed up for months and spread until it coloured sunsets all over the world.

What destroyed the first three islands that Anak Krakatau raised above the sea after 1927?

Erosion by the waves. The first cones were loose ash that the surf soon scattered, and only the fourth island, in 1930, outlasted it.

Small waves set off by Krakatoa were recorded on tide gauges as far away as which European waterway?

The English Channel. They arrived too soon to be the sea wave itself, so they are thought to have been raised by the pulse of air pressure passing overhead.

Which poet recalled Krakatoa's sunsets in his 1892 poem St. Telemachus, with its 'blood-red eve' and 'wrathful sunset'?

Alfred Tennyson. He asked whether 'the fierce ashes of some fiery peak' had been hurled so high they 'ranged about the globe', which is just what Krakatoa's dust had done.

Krakatoa's 1883 eruption killed some 36,000 people, so why did almost none of them die on the island itself?

Nobody lived there. The island had no settled population in 1883, so nearly all the dead were on the coasts across the water, drowned when the sea came ashore.

Satellite images taken days after the deadly 2018 tsunami showed Anak Krakatau's summit crater had become what?

A small bay. The cone had lost more than two-thirds of its volume and most of its height, and the sea now washed into what had been a crater some 340 metres up.

After Krakatoa's final explosions, what did the surrounding region go without for more than two days?

Daylight. So much ash hung in the air that the area stayed dark until 29 August, and skies were dimmed as far as 440 km from the volcano.

Poet Gerard Manley Hopkins published his vivid account of Krakatoa's sunsets in which science journal?

Nature. His letter on the strange twilights ran there in January 1884, one of the very few pieces he saw in print, since his poems stayed in manuscript until long after his death.