The Indonesian volcano which triggered a deadly tsunami when it erupted and collapsed a week ago is now only about a quarter of its previous size.
Scientists at Indonesia’s Centre for Volcanology and Geological Disaster Mitigation said Anak Krakatau now has a volume of 1.4 billion-2.4 billion cubic feet, having lost 5.2 billion-6.3 billion cubic feet of volume since the December 22 eruption.
The analysis shows the scale of the island’s collapse, shedding light on the power of the tsunami that crashed into more than 186 miles of coastline in Sumatra and Java.
More than 420 people died in the waves that reached up to 6.6ft in height, and 40,000 were displaced.
The centre said the crater peak was 360ft high on Friday compared to 1,108ft in September.
Experts have largely relied on satellite radar images to work out what happened to the volcano because cloud cover, continuing eruptions and high seas have hampered inspections. The centre said it would get more precise results from more visual inspections.
Authorities have warned residents to stay at least a mile away from the coastline of the Sunda Strait, which separates Java and Sumatra, because of the risk of another tsunami.
But experts now say another potential tsunami triggered by the volcano collapsing again would be less severe due to its reduced mass.
Anak Krakatau, which means Child of Kratakau, is the offspring of the infamous Krakatau volcano whose monumental eruption in 1883 triggered a period of global cooling.