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, reports BBC.

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, BBC reported.

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.