Technology & Science

Anak Krakatau volcano now a quarter of its pre-eruption size

Indonesia's Anak Krakatau volcano island — which erupted and collapsed a week ago, triggering a deadly tsunami — is now only about one-quarter of its pre-eruption size, scientists say.

Analysis shows scale of island's collapse, shedding light on power of tsunami that crashed into coastline

An aerial view of Anak Krakatau volcano during an eruption on Dec. 23. Scientists say the volcano is now only about one-quarter of its size after its eruption and collapse one week ago. (Nurul Hidayat/Antara Foto via Reuters)

Indonesia's Anak Krakatau volcano island — which erupted and collapsed a week ago, triggering a deadly tsunami — is now only about one-quarter of its pre-eruption size, scientists say.

Anak Krakatau now has a volume of 40 to 70 million cubic metres and lost 150 to 180 million cubic metres of volume since the Dec. 22 eruption and tsunami, according to Indonesia's Centre for Volcanology and Geological Disaster Mitigation.

The analysis shows the scale of the island's collapse, shedding light on the power of the tsunami that crashed into more than 300 kilometres of coastline in Sumatra and Java. More than 420 people died in the waves that were two metres or higher and 40,000 were displaced.

The centre said that the crater peak was 110 metres high as of Friday, compared with 338 metres 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.

The Anak Krakatau volcano, off the coast of Banten, Indonesia, erupts in a massive cloud of hot gasses and ash on Dec. 28. (Ed Wray/Getty Images)

Authorities have warned residents to stay at least a kilometre 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 Krakatau, is the offspring of the infamous Krakatau volcano whose monumental eruption in 1883 triggered a period of global cooling.

The Geospatial Information Authority of Japan (GSI) released these images showing the collapsed part of Indonesia's Anak Krakatau volcano island. (GSI)

Comments

To encourage thoughtful and respectful conversations, first and last names will appear with each submission to CBC/Radio-Canada's online communities (except in children and youth-oriented communities). Pseudonyms will no longer be permitted.

By submitting a comment, you accept that CBC has the right to reproduce and publish that comment in whole or in part, in any manner CBC chooses. Please note that CBC does not endorse the opinions expressed in comments. Comments on this story are moderated according to our Submission Guidelines. Comments are welcome while open. We reserve the right to close comments at any time.