How did a deadly tsunami hit the Indonesian coast without an earthquake before? | World

Andersen reported to the BBC that the shores of the islands had been hit by two waves without trembling.

"Suddenly, I saw this wave coming in and I had to run in. There were two waves, the first one was not so strong, I could escape it," he said. -he explains.

The second was devastating: it killed dozens of people and injured hundreds, and left hundreds of houses and buildings destroyed, according to the countdown Sunday morning.

No earthquakes have been recorded, which normally gives the authorities time to broadcast a tsunami warning.

Only the Anak Krakatoa volcano recorded explosions during the sixth and saturday. And as Andersen explains, "just before the waves hit the beach, there was no activity (volcanic)".

The wave was affected at 21:30 local time (14:30 GMT).

What then provoked this giant wave with devastating consequences for Indonesia?

In this photo: Anak-Krakatau volcano with increased activity, 2.5 hours before the href = "https://twitter.com/hashtag/tsunami?src=hash&ref_src=twsrc%5Etfw" url = "https: // twitter.com/hashtag/tsunami?src=hash&ref_src=twsrc%5Etfw "> # tsunami <! – > Waves have swept over parts of the coastal areas of West Java and South Sumatra. href = "https://twitter.com/hashtag/indonesia?src=hash&ref_src=twsrc%5Etfw" url = "https://twitter.com/hashtag/indonesia?src=hash&ref_src=twsrc%5Etw"> #indonesies < ! – > href = "https://twitter.com/hashtag/anyer?src=hash&ref_src=twsrc%5Etfw" url = "https://twitter.com/hashtag/anyer?src=hash&ref_src=twsrc% 5Etfw "> # anyer <! – > href = "https://t.co/0Xv3lQwAQ3" url = "https://t.co/0Xv3lQwAQ3" >> image.twitter.com/0Xv3lQwAQ3 <! – December 23, 2018

The experts are trying to determine precisely, but an initial badessment indicates an event triggered by the Krakatoa volcano.

Officials report that there has been a landslide underwater in the Sunda Strait, which divides the islands of Java and Sumatra, and that this has generated shockwaves.

The head of the Indonesian Disaster Control Agency, Sutopo Purwo Nugroho, gave this first explanation from information on the geological activity recorded before the tsunami.

On Twitter, he attributes this phenomenon to "a combination" of the submarine landslide caused by the Krakatoa eruption at high tide during the full moon.

Nugroho badured that tsunamis in the Sunda Strait are not common. Similarly, large eruptions of Krakatoa usually cause only low intensity tremors.

"There was no earthquake that could trigger the tsunami thereafter, and it is difficult to determine the cause," he said.

The volcanologist Jess Phoenix told the BBC that, during the eruption of volcanoes, the burning magma creates a crazy wave beneath the earth.

It can move and break colder rocks, sometimes causing large landslides.

As the Anak Krakatoa volcano is partially submerged, instead of causing a superficial slip, "it has generated an underwater landslide".

The phenomenon "pushes" water as it develops – with the potential to generate a tsunami.

Like every tsunami, a few minutes or hours go by before the waves reach the coast. In addition, the high tide of the full moon probably contributed to the strength of the waves.

In recent months, the activity of Anak Krakatoa volcano had increased.

The Indonesian Geology Agency said the volcano erupted for two minutes and 12 seconds on Friday, creating a cloud of ash rising 400 meters above the mountain.