When Anak Krakatau Blew Its Top...

Jan 23, 2019 By Saumya V, Writer Intern
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Exactly a month ago, on 22 December 2018, a devastating tsunami hit the west coastline of Java and Sumatra in  Indonesia.

There was no warning before the tsunami and people’s daily lives went on as usual until the tsunami struck. Over four hundred people were killed, and thousands more were injured. People lost their homes and possessions to the deadly waves of the tsunami.

The tsunami was also a grim reminder of the 2004 Christmas Day tsunami triggered by an earthquake in the Indian Ocean. Huge waves traveled across the ocean, killing nearly 226,000 people in 14 countries. See our article here

The Cause of the Tsunami

The cause for the recent Indonesian tsunami was an eruption from the volcano, Anak Krakatoa located between the islands Java and Sumatra.

The eruption weakened the southwest sector of the volcano which collapsed into the ocean. The volcano lost more than two-thirds of its height because of the landslide. The collapse of the volcano triggered huge ocean waves. People who were watching the volcano were not able to see the landslide.

The earthquake had immobilized the seismometers near the volcano. The readings of other seismometers were not strong enough to trigger a tsunami warning. Indonesians were not aware of the tsunami until the first huge wave crashed along the shores. Additionally, it was a full moon night, therefore tides were much stronger. This fueled the strength of tsunami even more.

Anak Krakatau

Anak Krakatau is the child of the volcano Krakatoa. Krakatoa destroyed itself in 1883 after eruption for the last time. This eruption was the deadliest volcanic eruptions recorded in history.

Many died because of the thermal blast caused by Krakatoa’s eruption and even more died because of the tsunamis that Krakatoa’s collapsed resulted in. All together, Krakatoa killed over thirty-six thousand people. There were also significant changes in the climate of the Earth because of Krakatoa’s collapse.

Forty-four years after the devastating Krakatoa eruption, in 1927, a group of fishermen spotted steam and debris from the collapsed caldera. After a few weeks, at the same location as Krakatoa, another volcano had begun to rise above the surface of the Earth. This volcano was named Anak Krakatoa, child of Krakatoa. Over the years, Anak Krakatoa has erupted occasionally but did not seem like a major threat.


A month after the tsunami caused by the collapse of Anak Krakatoa, Indonesia is grieving for the people killed in the tsunami. Many are still missing. The tsunami destroyed houses, building, boats, and ships. The Red Cross has been helping the survivors by bringing fresh water, food, clothes, and other necessary supplies to survivors.

Sources: BBC, WashingtonPost, NYTimes, LiveScience, Scientific American, Earthobservatory.sg