Krakatau: The island which vanished!

It was August 27, 1883. Nobody had thought that the Indonesian island of Krakatau was going to be blown apart that day. But, that is exactly what happened! On this fateful day, the Krakatau volcano erupted, making 75 per cent of the island just vanish into thin air. Today, 'Geo Facts' takes you on a journey to the Krakatau Island, which faced one of the deadliest disasters in the history of volcanic eruptions.

Indonesia has over 130 active volcanoes and tops the list among countries with volcanoes. The Krakatau Island is situated from a nearly east-west orientation in Java to a northwest-southeast orientation in Sumatra. Krakatau is one of several volcanic islands in the Sunda Straits, located above an active north-northeast trending fault zone. Although relatively small when compared to the largest volcanoes along the island arc, Krakatau and its associated volcanoes have shown the capacity to generate highly explosive eruptions.

If we delve into history, we can identify that this is not the first eruption, to take place on the island. In 416 AD, there has been the 'great eruption' which formed Krakatau, Verlaten and Lang Islands. The Krakatau Island comprised the volcanic summits, Rakata, Danan and Perbuwatan. From time to time, these have been slightly active. The melodrama started on May 20, 1883.

As a sign of the forthcoming threat, a column of ash and steam rose 11 km into the sky from the volcanic summit of Perbuwatan on this day, and ash fell into Southern Sumatra. From then onwards, there were regular, small scale explosions, sometimes within time intervals of ten to fifteen minutes.

In mid-June, the top of the Perbuwatan volcano was blown off in an eruption. It is recorded that by this time, there was a shroud of ash all around the volcano and the surrounding forests were burnt. The main eruption began on August 26 with a huge explosion which was heard 155 km away in Batavia.

A column of ash had risen 36 km high in four hours. In the afternoon and evening, the explosions became louder and more distinct throughout western Java. On August 27, the real tragedy took place with powerful explosions occurring at 6.36 am, 9.58 am and 10.45 am.

These colossal blasts literally blew Krakatau apart, making nearly 75 per cent of the island vanish below the surface of the ocean. The devastating blasts even created deadly tsunami waves up to 40m tall, which ravaged across the Sunda Strait, stripping away vegetation and claiming the lives of more than 36,000 people in various islands.

After 44 years of rest, Krakatau reawakened in 1927; this gave birth to a small island, which was made up of solidified lava and other minerals; and which is expanding gradually. This new island is called 'Anak Krakatau' (child of Krakatau). Anak Krakatau has erupted in most years since, and typically, these have been rather mild. Although they present little danger to the surrounding islands, the eruptions from Anak Krakatau are a constant reminder of the horrors of 1883.

Aravinda Dassanayaka

Fact file:

* The explosions were heard 4,653 km away on the Island of Rodriguez in the Indian Ocean.

* A hail of ash and stone covered 300,000 square miles or some 483 square kms within a radius of 150 kms.

* The eruption was heard in Philippines, Alice Springs, Rodriguez Island and Madagascar.

* The power of the eruption was estimated to 21,547.6 atom bombs multiplied.

* A bank of pumice (a very light rock formed from lava) floated to Durban, South Africa in September 1884, over a year after the eruption.

* Volcanic dust and gases reached the stratosphere and circled the world in two weeks, which made beautiful sunsets visible around the world.

* Two temporary islands named Steers and Calmejer were formed from pumice which were eventually eroded by the waves.

* The total number of fatalities was recorded at 36,417.

* A total of 165 villages were totally destroyed and another 132 damaged.