it became pitch black.
The map on the right shows Krakatoa as it was before the great eruption of 1833. Three major volcanoes existed on the island, Perboewetan, Danan(not shown but in the middle), and Rakata. Since the eruption and collapse of Ancient Krakatoa the chamber beneath these three volcanoes had begun to fill, heat up, and create enormous pressure. Of late, Perboewetan had been the most active.
The Beast Awakens
On May 20, 1883, a plume of smoke was seen rising over 10km above the island of Krakatoa. During the following summer months military and commercial vessels would also report seeing the cloud. By August, ash and pumice bars were found everywhere in the Sundra Straits. The minor eruptions on Krakatoa from May-August were from Perboewetan volcano and by the time of the main eruption Perboewetan had nearly been completely destroyed widening the caldera beneath the islands and building more pressure.
Opening Salvo, August 26, 1833
around 1:00pm in the afternoon, Krakatoa delivered the first in
a series of blasts that would continue throughout the day until
the climactic eruption on August 27th. This opening blast generated
and defining shockwave that alerted the nearby coastal villages
on the islands of Java and Sumatra. A column of black volcanic
gas rapidly ascended to a height of over 25km above Krakatoa. In
the coming hours as blasts intensified it would reach at least
35km. Later in the day the coastlines were hit with a series of
tsunamis generated by the ocean impact of pyroclastic flows coming
off the flanks of the island. Nothing of this would compare to
what the world would witness the following day.
At 5:30am the first of four cataclysmic explosions began on the island of Krakatoa. Tsunamis lashed out from the island pounding nearby coastlines and ash and pumice fell in droves on surrounding islands. At 6:44am a second massive blast came from Krakatoa unleashing similar effects. Finally at 10:02am the colossal blast took place that blew the island apart. Perboewetan and Danan erupted and fell into the emptying caldera 250m below sea level. Adding to the empty chamber was Rakata as half of the erupting volcano slid into the ocean displacing large volumes of and generating a massive tsunami. In total, 23 square kilometers of the island fell into the 6km wide caldera. The ground shook in the wake of the blast which was heard over 4500km and was estimated to be equal to the detonation of over 21,000 atomic bombs.
The Horizon Vanishes: Tsunamis
"...all of a sudden there came a great noise. We...saw a great black thing, a long way off, coming towards us. It was very high and very strong, and we soon saw that it was water" - From A. Scarth, 1999
the third and catastrophic explosion of Krakatoa, enormous tsunamis
were generated by the displaced water as the island collapsed into
the caldera. These waves moved with great speed across the Sundra
Straits reaching a height of around 40m tall before slamming into
the nearby coastlines. Smaller tsunamis had pounded the local villages
in the previous days eruptions but nothing compared to this mammoth
wave. Many small coastal islands were completely submerged and
as the wave hit the mainland islands of Java and Sumatra it ravaged
towns and villages while stripping away nearly all vegetation.
In some cases, whole towns of several thousand people were washed
away in a flash destroying and sign they had ever been there. Accounts
exist of villagers scrambling up inland hills to escape the waves.
Often only the small top of a hill would be spared by the enormous
current leaving former neighbors in great struggle with one another,
while trying to maintain a safe position from the waves.
Fire of the Mountain: The Pyroclastic Flows
When Krakatoa exploded hot ash and tephra were sent sprawling down the flanks of the volcano and into the Sundra Straits. These pyroclastic flows, essentially avalanches of fire and rock, stormed across the straits to distances of up to 40km engulfing passing ships and coastal villages. The flows traveled at speeds of over 100km/hr leaving little time for people to evacuate from the advancing surge. The flows were able to move quickly and a great distance for two reasons. These pyroclastic flows may have reached temperatures of over 700 degrees Celsius, which overland would scorch anything in its path. However, in the open ocean the pyroclastic flow will flash boil the water as it comes in contact with it allowing the entire surge to ride on a cushion of air. This lack of friction with water or land, often compared to and air hockey table, allows the flow to move with great speed and for a long time. It was the southern coast of Sumatra that was hit hardest by the flows. Of the over 36,000 deaths, around 4500 are contributed to the deadly pyroclastic flows which would have arrived just after the tsunamis. Most likely the 4500 who met their fate with the flows had reached high ground or shelter to avoid the rushing water only to be engulfed by fire and ash.
...And Into This World(Anak Krakatoa: The child of Krakatoa)
On December 29, 1927 debris began spouting out of the ocean surface above the collapsed caldera of Krakatoa. The debris continued to spout till finally on January 26, 1928 the rim of a new volcanic cone emerged from below sea level. Indeed, after 44 years of silence Krakatoa began erupting anew giving birth to Anak Krakatoa, the child of Krakatoa, which has been erupting steadily ever since. To this day the many eruptions of Anak Krakatoa have been mild and expanded the island to base of 2km and over 200m above sea level. Today you may go to the Sundra Straits and step foot on young volcano's rim. And perhaps there as you look across the sea to the coasts of Java and Sumatra you may be able to feel, ever so slightly, the power of the awesome events that took place there just over a century ago.
2. Scarth, Alwyn. Savage Earth. HarperCollins Publishers Ltd. Copyright 1999.
3. Carey, Steven. Geology Boulder: "Tsunami deposits from major explosive eruptions; an example from the 1883 eruption of Krakatau." Geological Society of America. Copyright 2001.
4. KRAKATAU, INDONESIA (1883). San Diego State University.
5. KRAKATOA. Travsworld Entertainments.
6. Krakatau Volcano National Park, Nasa's Earth Observatory.
Author: Michael Bubb
The Regional and Local Geography of Krakatoa
The Eruptions Begin
Avalanches of Fire
8. Krakatau Volcanic Island.
9. What happened in the Krakatoa eruption in the 1800's?
10. Krakatau (Krakatoa) Island
Copyright © 2004 Earlham College. Revised April 18, 2004 . Send corrections or comments to firstname.lastname@example.org