Indonesia tsunami: Flights rerouted to avoid erupting Anak Krakatau volcano as alert level raised

Indonesian authorities have raised an alert for the erupting Anak Krakatau volcano to the second-highest level and ordered all flights to steer clear, days after it triggered a tsunami that killed at least 430 people.

The country’s geological agency has imposed a three-mile exclusion zone around the volcanic island and urged people to stay away from the coast amid fears a crater collapse could trigger further deadly waves.

A crater collapse at high tide on Saturday sent waves up to six metres high (20ft) smashing into the coast on the Sunda Strait, between the islands of Java and Sumatra.

The tsunami struck without warning, taking people by surprise in a nation that regularly suffers earthquakes, volcanic eruptions and landslides.

No earthquake shook the ground beforehand and the waves surged inland at night on a holiday weekend as people enjoyed beach concerts and other coastal activities.

Nearly 22,000 people have been displaced by the disaster, with about 1,500 injured and 159 still missing.

Authorities have warned that the crater of Anak Krakatau, or “child of Krakatoa”, remains fragile. The volcano has been rumbling on and off since July but has been particularly active since Sunday, spewing lava and rocks and sending huge clouds of ash up to 3,000 metres into heavily overcast skies.

“Since 23 December, activity has not stopped,” said Antonius Ratdomopurbo, secretary of the geological agency. “We anticipate a further escalation.”

A thin layer of volcanic ash has been settling on buildings, vehicles and vegetation along the west coast of Java since late on Wednesday, according to images shared by Indonesia’s national disaster mitigation agency.

Authorities said the ash was not dangerous but advised people to wear masks and goggles when outside, and flights have been rerouted.

The civil aviation authority said no airports would be affected. Indonesia’s capital, Jakarta, is about 96 miles east of Anak Krakatau.

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 tsunamis and lowering the global surface temperature by 1C with its ash.

Anak Krakatau, the island that emerged from the resulting hollow in 1927, has been growing ever since.

Indonesia is a vast archipelago that sits on the Pacific “Ring of Fire”, the site of many earthquakes and volcanic eruptions. This year, the country has suffered its worst annual death toll from disasters in more than a decade.

The latest has evoked memories of the 2004 Indian Ocean tsunami, triggered by an earthquake on Boxing Day, which killed 226,000 people in 14 countries, including more than 120,000 in Indonesia.

Warning systems were subsequently set up but they have failed to prevent further disasters, often because apparatus has not been maintained properly, while public education and tsunami preparation efforts have been patchy.

Ramdi Tualfredi, a teacher in the village of Cigondong, on Java’s west coast, said efforts to prepare communities for tsunami had “totally failed”.

He said: “There were no preparations. I didn’t get information from anywhere.” He added there had been little help for residents since disaster struck.

Most of the thousands of people displaced are staying in crowded shelters.

Aid is getting through and the government has declared a state of emergency until 4 January to help with the distribution of assistance.