New cracks have emerged on the Anak Krakatau volcano, prompting the Indonesian authorities to urge those in the vicinity to be on the alert in case a collapse sets off another tsunami.
Dr Dwikorita Karnawati, head of the Meteorology, Climatology and Geophysics Agency, told reporters yesterday: "Of course the hope is that it will not be like what happened (on Dec 22), but we ask the public to be vigilant when they are in the 500m zone around the coast."
A section of the volcano's slope collapsed after it erupted that day, sliding into the ocean and displacing massive amounts of water that sent waves up to 5m high crashing into densely populated areas on Sumatra and Java islands.
Dr Dwikorita said the two new cracks appeared after the volcano's height dropped from 338m to 110m following its eruptions. "From the latest we have seen from the air, the mountain is sloping and smoke is rising from beneath the sea water. And on the body of the mountain... there are cracks that continue to emit smoke," she said.
"The cracks are certainly deep", unlike normal gaps, and they are located close to each other, she added. "If there is another eruption, the cracks might connect and weaken the slope, causing part of the mountain to collapse again," said Dr Dwikorita.
The part that could collapse has a volume of about 60 million cubic m - smaller than the 90 million cubic m of slope that slid into the Sunda Strait on Dec 22, she said.
Though new cracks have been spotted, volcanic activity has been decreasing, added Dr Dwikorita.
President Joko Widodo spent the first working day of the year in Lampung on Sumatra Island. It was one of the areas worst hit by the tsunami that left more than 430 people dead and over 14,000 injured.
He has ordered the building of new housing in the regency of South Lampung, about 400m from flattened homes. About 110 people died in the regency. The high toll was because many homes were on the beach.
"Housing will be relocated because this location is vulnerable to tsunamis," Mr Joko told reporters.
And the government hopes to include disaster management in elementary and high schools.
"Disaster education must start this January, especially for regions where there is a high possibility of big disasters," he said.