People gathered in prayer and visited mass graves in Indonesia’s Aceh province on Thursday to mark 20 years since the mass attack tsunami in the Indian Ocean hit the region in one of the worst natural disasters in modern history.

Many wept as they placed flowers at a mass grave in the village of Ulee Lheue, where more than 14,000 unidentified tsunami victims were buried. It is one of several mass graves in Banda Aceh, the capital of Indonesia’s northernmost province, which was one of the areas hardest hit by the 9.1-magnitude earthquake and the massive tsunami it caused.

“We miss them and still don’t know where they are. All we know is that we visit the mass grave in Ulee Lhue and Siron every year,” said Muhamad Amirudin, who lost two of his children 20 years ago and never found their bodies.

“This life is only fleeting, that’s why we try to be useful to others,” said Amirudin while visiting the grave with his wife.

Another man, Nurkhalis (52), told the Reuters news agency that his wife, children, parents and in-laws were all swept away by the tsunami.

“Although time has passed, the same feeling follows us on this date, especially those of us who lost our family then,” he said.

A strong earthquake off the coast of the Indonesian island of Sumatra on December 26, 2004 caused a tsunami that killed about 230,000 people in a dozen countries, reaching as far as East Africa. Waves up to 100 feet high carried away almost everything – and everyone – in their path.

There were about 1.7 million people displacedmainly in the four worst affected countries: Indonesia, Sri Lanka, India and Thailand.

More than 170,000 people died in Indonesia alone.

Although 20 years have passed, survivors in Indonesia are still mourning the loved ones they lost to the giant wave that flattened buildings as far as the provincial capital of Banda Aceh.

Hundreds of people gathered for prayer at the Baiturrahman Mosque in the center of Banda Aceh. Sirens sounded throughout the city for three minutes to mark the time of the earthquake.

Indonesia, which is located along the faults that form Pacific “Ring of Fire”, it is particularly vulnerable to earthquakes and tsunamis. It was tolerated another disaster in 2018 when the huge waves caused by the earthquake in Sulawesi, killing thousands.

In 2004, the infrastructure in Aceh was rebuilt and is now more resilient than before the tsunami hit. Early warning systems are installed in coastal areas to warn residents of impending tsunamis, giving crucial time to seek safety.

The reconstruction efforts were made possible by the support of international donors and organizations, which contributed significant funds to help the recovery of the region. Schools, hospitals and basic infrastructure destroyed in the disaster have been rebuilt.

In Thailand, people gathered for a memorial ceremony in Ban Nam Khem, a small fishing village in Phang Nga province that bore the brunt of the country’s devastating wave.

The tsunami claimed the lives of more than 8,000 people in Thailand, including many missing, leaving a deep scar in the nation’s history. Almost 400 bodies have not yet been retrieved.

Mourners shed tears and comforted each other as they laid flowers at the tsunami memorial in the village. About 300 people joined the modest ceremony with Muslim, Christian and Buddhist prayers.

Urai Sirisuk said she avoids Coastal Memorial Park the rest of the year because the loss of her 4-year-old daughter still cuts deep every time she’s reminded of it.

“I have the feeling that the sea took my child away. I’m very angry about it. I can’t even put my foot in the water,” she said.

But, she said, “I still hear her voice in my ears, calling me. I can’t leave her. That’s why I have to be here, for my child.”

In India, hundreds gathered at Marina Beach in the southern city of Chennai in Tamil Nadu state. They poured milk into the sea to propitiate the gods and offered flowers and prayed for the dead while drums beat in the background.

According to official figures, 10,749 people were killed in India, including nearly 7,000 people in Tamil Nadu alone.

“It’s been 20 years since the tsunami,” said 69-year-old Sadayammal, who uses only one name. We are here to honor the people who lost their lives.

In Sri Lanka, survivors and relatives of tsunami victims gathered in the coastal village of Pereliya to lay flowers at a memorial to the nearly 2,000 passengers who died when their train, the Queen of the Sea, was hit by a wave. It is believed that only a few dozen people survived.

Anura Ranjith joined mourners to pay tribute to his younger sister Anula Ranjani and her 9-year-old daughter who were passengers on the train. Ranjith never heard from them again after that day.

“I have been looking for them everywhere for years, and there is still no information about them. Their loss is a great sadness and pain for me. I am still grieving,” he said.

In total, more than 35,000 people died in Sri Lanka in the tsunami. On Thursday, people across the country observed two minutes of silence to honor those who lost their lives.

There was no warning at the time, but in the years following the 2004 disaster, a tsunami warning system it was set up to protect the region. A network of undersea earthquake-detecting seismometers, along with tide gauges and ocean buoys, can pick up early signals of tremors that generate tsunamis, and improved communications networks help relay those warnings to officials around the world.