Earth science: Signs of activity from Anak Krakatau prior to collapse

Prior to the collapse of a section of the volcano Anak Krakatau in December 2018, which triggered a deadly tsunami, it exhibited several signs of activity in the months leading up to the event. A study, published in Nature Communications today, notes that at the time, and when considered individually, none of the anomalies would have been conclusive enough to predict the events to come, but the observations could prove useful in the future.

Anak Krakatau is an island volcano in Indonesia; a section of which collapsed on 22nd December 2018, triggering a tsunami that killed over 430 people and displaced more than 30,000, with what was thought little advanced warning.

Thomas Walter and colleagues show that there were several signs of activity at Anak Krakatau prior to the 22nd December events. They report a gradual seaward motion of its southwestern flank from January 2018, which was accompanied by an intense phase of thermal activity initiated at Anak Krakatau on the 30th June 2018, and an increase in the island’s surface area in the months leading up to the event. The authors suggest that these factors may help explain why a flank of the volcano collapsed. These new observations could help to improve monitoring for potential flank collapse on other island volcanoes and aid in refining early warning technologies.