Indonesian authorities urged people to avoid the coast in areas where a tsunami killed at least 430 people over the weekend in a fresh warning.
The big waves that followed an eruption on a volcanic island hit communities along the Sunda Strait at the weekend.
The eruption of Anak Krakatau, or "Child of Krakatoa," is believed to have set off a large landslide on the volcano, apparently on its slope and underwater, displacing water that slammed into Java and Sumatra islands.
Indonesia's Meteorology, Geophysics and Climatology Agency asked people yesterday to stay at least 500m and up to 1km from the coastline along the strait, which lies between the two islands.
The agency was monitoring Anak Krakatau's eruptions as stormy weather and high surf continued to plague the area, said agency head Dwikorita Karnawati.
"All these conditions could potentially cause landslides at the cliffs of the crater into the sea, and we fear that that could trigger a tsunami," Karnawati said. She asked that communities remain vigilant and not to panic.
The warning was reiterated by the country's disaster agency.
The tsunami struck without warning, taking people by surprise even in a country familiar with seismic disaster. No big earthquake shook the ground beforehand, and it hit at night on a holiday weekend while people were enjoying concerts and other beach and resort activities.
It was a sharp contrast to the disaster that struck 14 years ago off the northwestern tip of Sumatra Island.
An enormous magnitude 9.1 earthquake rocked the area the morning after Christmas, creating gigantic waves that surged far inland and swallowed everything in their path. The wall of water killed some 230,000 people in a dozen countries, more than half in Indonesia's Aceh province.
The devastation was vast, and the disaster was among the worst in recent history.
Last weekend's event, coupled with an earthquake and tsunami in September on Indonesia's Sulawesi island that killed at least 2100 people, triggered flashbacks for some who survived the 2004 tragedy.
"When it happens, I always remember what we have been through," said Qurnaty, 54, who lost her home and several family members to the 2004 waves in the hard-hit provincial capital of Banda Aceh.
Qurnaty prayed with surviving family members at a mass grave there on yesterday's anniversary. "Every time I see them (on TV), I feel really, really sad. All we can do from here is to pray for them," she said.
Though recovery was slow, some victims of the latest tsunami said they remember the resilience of the Acehnese people, which gives them hope that they too can rebuild their homes and their lives.
"I am scared. I am traumatised by the tsunami that I only knew before from the news," said Kusmiati. "Now I know how horrifying a tsunami is."
Her face was still bruised and her legs swollen after she and her husband managed to survive being hit and dragged under by the waves after fleeing a beach villa in Carita, where they were working.
Beaches were largely empty in the area, which is typically crammed with tourists, and police patrolled on motorbikes, warning people to stay away from the coast. Some residents defied the warning, returning to what was left of their homes to begin cleaning up as heavy rain fell and waves pounded the shore.
"I am still afraid that the tsunami will return, so when dark comes, I stay at a temporary shelter on the hill," said Rohayati, who worked to salvage what was left of her battered house, 300m from the sea. "I hope the government can provide a tsunami warning, like a siren, for people living in coastal areas so we can be alerted of a potential tsunami and have time to save ourselves."
The country's system of tsunami detection buoys — deployed after the 2004 disaster — has not worked since 2012, with some units being stolen or vandalised.
Karnawati, of the meteorology agency, said that because the tsunami was caused by volcanic activity, it would not have been picked up by the system's seafloor sensors, which monitor movement from conventional earthquakes responsible for most of Indonesia's tsunamis.