Anak Krakatau: Indonesian volcano's dramatic collapse

[nitpicker]

https://www.bbc.com/news/science-environment-46707731

Anak Krakatau: Indonesian volcano's dramatic collapse

By Jonathan Amos
BBC Science Correspondent

7 hours ago

The scale of the dramatic collapse of the Indonesian volcano that led to last Saturday's devastating tsunami in the Sunda Strait is becoming clear. Researchers have examined satellite images of Anak Krakatau to calculate the amount of rock and ash that sheared off into the sea.

They say the volcano has lost more than two-thirds of its height and volume during the past week. Much of this missing mass could have slid into the sea in one movement. It would certainly explain the displacement of water and the generation of waves up to 5m high that then inundated the nearby coastlines of Java and Sumatra.
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The Centre of Volcanology and Geological Hazard Mitigation (PVMBG) has been studying pictures from a number of radar satellites, including the European Union's Sentinel-1 constellation and the German TerraSAR-X platform. Radar has the advantage of being able to see the ground day or night, and to be able to pierce cloud. The capability has allowed some initial measurements to be made of Anak Krakatau's lost stature, in particular on its western side.

What was once a volcanic cone standing some 340m high is now just 110m tall, says the PVMBG. In terms of volume, 150-170 million cubic metres of material has gone, leaving only 40-70 million cubic metres still in place.
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