The 150m-high tsunami last year everyone missed

A tsunami wave that towered 150m into the sky devastated an Indonesian island in December last year, and there's a good chance you heard nothing about it.

That's because the island was uninhabited and no one was killed, scientists say.

It was triggered by the eruption of Anak Krakatoa in late December. Four-hundred people lost their lives when the wave hit Sumatra, by which point it had reduced to between five and 13 metres. 

But analysis by researchers at Brunel University London and the University of Tokyo show the wave was initially up to 150m tall.

"When volcanic materials fall into the sea they cause displacement of the water surface," said study leader Dr Mohammad Heidarzadeh, an assistant professor of civil engineering at Brunel. 

"Similar to throwing a stone into a bathtub - it causes waves and displaces the water."

So much material was displaced in the eruption, Anak Krakatoa lost more than two-thirds of its height - dropping from 338m to 110m, so would have been dwarfed by the tsunami it created.

When the wave hit the first island, it was still 80m high.

"Fortunately, nobody was living on that island," said Dr Heidarzadeh.

When Krakatao erupted in 1883, it created a tsunami that was still a whopping 42m high when it hit land, killing 36,000 people. 

The new study was published in journal Ocean Engineering.