JAKARTA - Indonesia on Thursday (Dec 27) ordered flights to steer clear of Anak Krakatau as it raised the danger level of the erupting volcano to the second-highest level and widened a no-go zone around it, heightening fears of another natural disaster striking the tsunami-hit coastal areas around Sunda Strait.
The national geological agency raised the alert level of Anak Krakatau to the second-highest level on a four-level scale, with level 4 being the highest.
"The affected flights (around Anak Krakatau) have been diverted and given alternative routes," said Mr Yohanes Harry Douglas, spokesman for government air-traffic control agency AirNav, in a statement.
Flights to and from Soekarno-Hatta, Indonesia's main international airport just outside Jakarta, continued to operate normally.
The capital, Jakarta, is about 155km east of the volcano.
The volcano, whose name means "child of Krakatau", has been rumbling on and off since July but has been particularly active since the weekend.
The volcano has increased its activities in the past few days, spewing high columns of ash of up to 3,000m that fell on nearby cities even as aid workers and rescuers struggle to reach communities reeling from the devastation wreaked by last Saturday's killer waves.
At least 430 people were killed, with 1,495 people injured and another 159 were missing after an eruption at the volcano triggered killer waves which slammed into coastal areas in western Java and south Sumatra. Nearly 22,000 people have been evacuated and are living in shelters.
"Since December 23, activity has not stopped... We anticipate a further escalation," said Mr Antonius Ratdomopurbo, secretary of the geological agency.
A thin layer of volcanic ash has settled on the houses, buildings, vehicles and vegetation along the west coast of Java since late on Wednesday, according to images shared by the national disaster mitigation agency.
The authorities said the ash was not dangerous, but advised local residents to wear masks and goggles when they are outdoors.
Last Saturday, an eruption at the volcano in the Sunda Strait which separates Java and Sumatra caused a section of the crater to collapse and slide into the ocean, displacing a large volume of water and triggering waves as high as 5m.
The authorities have warned that the crater of Anak Krakatau remains fragile, raising fears of another collapse and tsunami, and have urged residents to stay away from the coast.
They have expanded the current 2km no-go zone around Anak Krakatau to 5km in radius.
In 1883, the volcano then known as Krakatoa erupted in one of the biggest blasts in recorded history, killing more than 36,000 people in a series of tsunami and lowering the global surface temperature by 1 deg C with its ash.
Anak Krakatau is the island that emerged from the area in 1927 and has been growing ever since.
Indonesia, which sits on the Pacific "Ring of Fire", has suffered its worst annual death toll from natural disasters in more than a decade.
Last Saturday's volcano-triggered tsunami was the third major one after a series of powerful earthquakes rocked the island of Lombok in July and August and a quake-tsunami in September that killed around 2,200 people in Palu on Sulawesi Island.
The latest tsunami disaster, coming during the Christmas season, evoked memories of the Indian Ocean tsunami triggered by an earthquake on Dec 26, 2004, which killed 226,000 people in 14 countries, including more than 120,000 in Indonesia.
