Today in Geological History; 28th August

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Silence of Krakatoa

One of the first times volcanoes became real in my mind was a Sunday afternoon in my early teens. Sat in the living room after lunch, my Nan and I flicked through the channels until she found an old movie to nod off to. Made in the late 1960’s, it was one of those old films which would usually have me wonder off to my room but even with the poor special effects, I stayed, hooked as it depicted and exploding island. Soon after I came across the film Dante’s Peak intrigued by the first film, I wanted to see more. I began to question, to google the fact from the fiction, see the science behind the screen. It amazed me to learn unlike Dante’s Peak, Krakatoa East of Java was actually based on true events.

Krakatoa explosion1. Popular rendering of the events of 27th August 1883.

As early as May of 1883 reports from several trading ships around the Indonesian coast line reported activity around the island of Krakatoa. Ash clouds mostly, as well as some earthquakes but this was all pretty usual in this region. This changed rapidly. By 11th August there were at least three major ash plumes rising from the three main vents (Danan, Perboewatan and a new vent between the two.) Around 1pm local time on the 26th August the volcano entered its paroxysmal phase; explosions heard across the Sunda Strait every ten minutes or so, with a small tsunami hit the shores of Java and Sumatra that evening.

The climax begin at 5.30 on the morning of the 27th as the first explosion was at Perboewatan, generating a tsunami headed straight to Telok Betong. At 6:44 A.M, Krakatoa exploded again on Danan, with the resulting tsunami propagating east and west. The largest explosion, at 10:02 A.M, was so violent that it was heard 3,110 km (1,930 mi) away in Perth, Western Australia, and the Indian Ocean island of Rodrigues near Mauritius (4,800 km (3,000 mi) away). Pyroclastic flows began to ravage the Sunda Strait and some of the Sumatran coast line. At 10:41 A.M, a landslide tore off half of Rakata, causing the final explosion. This blast was so loud it ruptured the eardrums of sailors throughout the Sunda Strait, The pressure wave radiated across the globe and was recorded on barographs all over the world, which continued to register it up to 5 days after the explosion. Readings showed that the shock wave from the final explosion reverberated around the globe 7 times and it has been noted as the loudest noise ever recorded in nature.

Krakatao2. Current map of the islands with the outline of the island prior to the eruption.

The morning of the 28th August Krakatoa was silent.

After months of activity and an explosive finish all fell quiet on what little was left of the island. But locals could not rest so easy as the mountain. The official death toll released by Dutch authorities (who had power over Indonesia at the time) was 36,417 but many believe the long term figure was as high as 120, 000. Bodies were still washing ashore as far as Africa almost a year later as tsunami waves simply carried people away. Several settlements were completely destroyed to the point they were never repopulated and reverted to jungle that is now the Ujung Kulon Nation Park.

Effects were further reaching than just the Sunda Strait. An estimated 20 million tonnes of sulphur dioxide as well as other green house gasses where emitted in to atmosphere inducing a volcanic winter. For the next few years there was an average temperate drop of around the globe of 1.2 degrees Celsius with climate patterns not fully returning to normal until 1888.

Krakatoa also was also the first natural disaster to make world wide news. The VEI 6 eruption happened in the age of the new under seas telegraph wires and for the first time people were learning about events world wide and not just in their own countries.

SP017001_1648260a3. Front page of British newspaper depicting the destruction of the island.

The Krakatoa story does not just end there either. An event similar is believed have happened before, around 416 AD, causing collapse of the ancestral Krakatoa edifice. After the 1883 eruption half the island was completely gone but this is no long the case. Looking at figure 1. there is an island labelled Anak Krakatoa (child of Krakatoa). The volcano now stands over 180 metres above sea level which emerged and has been growing since only 1927.

untitled 4. Anak Krakatoa in 2012.

This volcano has continued to amaze me ever since my fascination with volcanology began all those years ago, the background image of this blog is even of an eruption there in 2012. To learn further about the events of 1883 Simon Winchester publish a fabulous book ‘Krakatoa; The Day the World’ (2003).  The book beautifully depicts the social and economic climate in Indonesia in those early years and the true devastation when the Earth releases its power in such a way.

For a few moments, it seemed unlikely that they would make it. For at 8 p.m., as a hail of pumice began to rain down, the waves began their first orgy of destruction. They were eventually to reach well over a hundred feet in height, and right from the start even the precursors of the mighty waves, even the first tentacle-feelers of water, did the most amazing damage.

1. http://www.theguardian.com/news/2013/aug/25/weatherwatch-krakatoa-explosion-tsunami-disaster-dust-sunsets Accessed 27/08/14

2. http://www.meteoportaleitalia.it/scienze/scienze/vulcanologia/7057-le-grandi-eruzioni-del-passato-parte-1-la-tragedia-del-krakatoa.html Accessed 27/08/14

3. http://www.thesun.co.uk/sol/homepage/hold_ye_front_page/4696540/Krakatoa.html Accessed 27/08/14

4. http://wwalert.wordpress.com/2012/01/09/7-indonesian-volcanoes-on-alert/ Accessed 28/08/14

 

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About Melly Rocks

20 something living in London while doing my Natural Science BSc with the Open University. Wannabe geologist and trainee volcanologist. Living life to the full and following the rocky road to my dreams...

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