Tsunami from Anak Krakatoa eruption in Indonesia was 100 metres high, say scientists

Over 400 people died when Indonesia’s Anak Krakatoa volcano erupted last December, triggering a massive tsunami

Scientists simulated the wave’s speed and direction, estimating it could even have reached a height of 150 metres

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An aerial picture showing Anak Krakatoa volcano in Indonesia erupting on December 23, 2018, which triggered a massive tsunami with waves of at least 100 metres high, according to researchers. Photo: AFP

Published: 2:15pm, 21 Dec 2019Updated: 10:06pm, 21 Dec 2019

The tsunami unleashed by the eruption of Indonesia’s Anak Krakatoa volcano on December 22 last year towered at least 100 metres high and possibly even reached a height of 150 metres, according to a new study by scientists in Tokyo and London.

More than 400 people on surrounding islands were killed by the tsunami, which was triggered by the volcanic eruption and the collapse of a section of the crater wall, but the death toll could have been significantly higher if the island closest to the volcano had been inhabited.

In a paper in the journal Ocean Engineering, scientists from the University of Tokyo and Brunel University London used sea-level data from five locations surrounding Anak Krakatoa to validate computer models that simulated the speed and direction of the tsunami from the time the crater wall collapsed until it made landfall.

A plume of ash rises as Anak Krakatoa volcano erupts on December 23, 2018, triggering a massive tsunami. Photo: Reuters

Debris from the collapsing volcano – which stood 338 metres tall before the eruption but was just 110 metres tall by the time the volcanic activity subsided – displaced water that initially rose between 100 and 150 metres above the surface of the ocean.

That wave quickly shrank, however, as gravity pulled it downwards and friction was generated between the tsunami and seabed.