Indonesia on Thursday rerouted flights passing through the vicinity of the Anak Krakatau volcano after it spewed large amounts of ash. The Anak Krakatau volcano had erupted on December 22, triggering a landslide that caused a tsunami, which hit parts of Java and Sumatra, killing more than 430 people and leaving nearly 1,500 injured.
The Indonesian government has raised the alert level for the Anak Krakatau volcano to red, the second-highest level, and imposed a 5km exclusion zone around the mountain.
Meanwhile, search and rescue operations continued in the areas hit by the tsunami even as officials feared another tsunami being caused by the ongoing volcanic activity on Anak Krakatau.
The authorities warned residents to stay away from coastal areas. Residents of the towns of Cilegon and Serang in Java were asked to wear masks and glasses outdoors as winds were carrying ash and sand spewed by Anak Krakatau.
The tsunami "appears to have been caused by an underwater collapse" of part of Anak Krakatau, said David Rothery, a professor of planetary geosciences at Britain's Open University.
Anak Krakatau is an island that emerged around 1928 in the crater left by Krakatoa, whose massive 1883 eruption killed at least 36,000 people.
