The number of people killed in the twin catastrophes climbed to almost 500 on Sunday, as dozens more bodies were found in the tsunami-ravaged Mentawai islands.

Indonesia, a vast island nation of 235 million people, is prone to earthquakes and eruptions because it straddles a series of fault lines and volcanoes known as the Pacific “Ring of Fire.”

Warning sirens blared, and people sprinted down the slopes of Mount Merapi or sped off in cars and trucks while others who had returned amid a brief lull to check on their livestock jumped into rivers hoping to protect themselves when the volcano erupted, local disaster official Rusdiyanto said.

No new casualties were immediately reported in the latest blast, which sent massive clouds of ash down the less-populated southern and eastern slopes, an official said. The volcano has killed 38 people since it began erupting Tuesday.

Authorities have been frustrated that many of the more than 53,000 evacuated since the eruptions began Tuesday keep going back during the daylight hours, ignoring warnings of the danger. More than 2,000 troops had to be called in Saturday to force men, women and children to leave.

Residents of the once-fertile slopes of Merapi — which means Fire Mountain — say they’re just trying to salvage something of their lives.

“My farm has been destroyed by volcanic debris and thick dust. … All I have left now are my cows and goats,” said Subarkah, who lives less than two miles (three kilometers) from the peak. “I have to find grass and bring it up to them, otherwise they’ll die.”

The 46-minute eruption Sunday shot dust about a mile (two kilometers) into the air and a cloud of hot ash a half mile (a kilometer) down Merapi’s eastern and southern slopes, said Surono, chief of the Center for Volcanology and Geological Hazard Mitigation.

“There should be no casualties from the new eruption because the flow of hot ash is lower and far from populated areas,” Surono said.

The airport in the city of Solo, 25 miles (40 kilometers) east of Merapi, was forced to close Sunday for at least an hour due to volcanic dust that fell like rain, said Bambang Ervan, a spokesman for the transportation ministry. He said the facility would reopen later Sunday night.

National airline Garuda Indonesia also rerouted flights from the airport at Yogyakarta indefinitely out of concerns volcanic dust from Merapi, 18 miles (30 kilometers) to the north, would damage plane engines, airline spokesman Pujobroto said.

In the last century, more than 1,400 have been killed by Merapi, one of the world’s most active volcanos.

Since Saturday’s large eruption, the volcano has had 63 lava bursts and nine small gas emissions, said Subandrio, an official with the volcano’s monitoring agency.

“The trend seems to be that the volcanic activity is increasing,” he said.

Surono warned that heavy rain Sunday increased the danger of another larger eruption because water falling into the fiery crater can create sudden vapor pressure in the lava dome, he said.

More than 800 miles (1,300 kilometers) to the west, a break in stormy weather made it possible for boats and helicopters to ferry aid to the most distant corners of the Mentawai Islands, where some coastal communities were pounded by waves up to 18 feet (six meters) high last Monday. The tsunami swept entire villages to sea, and hundreds of homes, schools, churches and mosques were destroyed.

A military helicopter evacuated badly injured survivors who had languished in an overwhelmed hospital with only paracetamol to ease their pain, said Ade Edward, a disaster management official. Among those evacuated was a baby girl born in a shelter after the tsunami and a 12-year-old girl with a life-threatening chest wound.

A C-130 transport plane, six helicopters and four motorized longboats were ferrying food and emergency supplies Sunday, he said.

Relief efforts were brought to a complete stop Saturday by stormy weather and rough seas.

“We’re really glad to finally see the relief workers, doctors and rescue teams able to reach devastated areas,” Edward said, adding that two navy ships arrived Sunday with many more police and soldiers deployed to speed up relief efforts.

The tsunami death toll climbed to 449 on Sunday with the discovery of dozens more bodies, said Nelis Zuliastri from the National Disaster Management Agency.

The fault that ruptured Monday, running the length of the west coast of Sumatra island, also caused the 9.1-magnitude quake that unleashed a monster tsunami around the Indian Ocean in 2004, killing 230,000 people in a dozen countries.

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Associated Press writers Achmad Ibrahim and Kristen Gelineau in the Mentawai islands and Niniek Karmini in Jakarta contributed to this report.