The only way Yasmine Habash can describe the Langtang valley is “tragically beautiful”. Even in a country that has seen so much devastation and so much personal heartbreak, what happened to the village of Langtang is in a different league. Moments after the earthquake struck, a massive expanse of ice fell thousands of feet, creating an avalanche that wiped out a community where 400 people lived and where, at that moment, nearly 100 foreign trekkers are believed to have been.

In a matter of seconds, Langtang village was wiped off the face of the Earth and, in Kathmandu this week, Habash described what it was like to visit the place where it used to be: “It’s so stunning up there. But I just couldn’t look at the beauty of it because it hurt knowing that so much pain is in that area.”

The pain is because her 57-year-old mother, Dawn, was trekking in Langtang and still has not been found. Official search-and-rescue attempts were recently called off – the authorities said it was too dangerous to continue. But last week Habash, 30, told how she had spent six days searching for her mother in an otherwise desolate and empty valley. She gave up only when the Nepalese army insisted on evacuating her earlier this week. “It was deserted. There were a few local people who were there searching for relatives, but otherwise it was just us. The US embassy told us not to go, but I was determined to find her.”

It was an incredibly risky – some would say foolhardy – thing to do. At the same time as Habash was in the valley with her boyfriend, Reid Harris, 32, and a local guide, 23-year-old Sunil Tamang, I visited Shyaphru Besi, at the head of the trail, a ghost village of ruined hotels and destroyed houses, a continuous landslide from the mountain above. In the neighbouring town of Dunche, the chief conservation officer of the national park told me: “You cannot go into the valley now. It is too dangerous. Another avalanche or landslide could happen at any time.”

In fact it did. On Habash’s third day, just after she and Harris had left the valley floor, another avalanche hit, sweeping across the ground they had spent all day searching. Still they continued to look above the slide until they were forcibly evacuated, narrowly missing another massive avalanche caused by Tuesday’s 7.3 magnitude quake.

All over Kathmandu, the relatives of missing trekkers are still gathering in embassies around the city. Briton Greg Carapiet, the father of a missing 23-year-old student, Mat, described how he, too, had been on the ground in Langtang village the week before trying to search for his son. “I desperately wanted to stay and search for Matt among the fallen rocks and boulders,” he said. But he was forced to leave. “I felt I had failed my son. I was distraught.”

On the last day of the official search, Matt’s body was found and last week the family were finally able to bring him home. “But the whole thing has been so frustrating. I just wanted to see Matthew’s body before he was repatriated and I wasn’t allowed. It was an awful, awful day. I managed in the end but it was through sheer perseverance and not giving up.”

No one knows exactly how many people are still missing in the area, but it is estimated that 183 Nepalese and 50-70 foreigners have died, and at least 100 people, both foreign and Nepalese, are still unaccounted for.

When the official search was called off, Habash and her family took matters into their own hands. They launched a fundraising site, and she hired a helicopter and flew over the place where the village used to be: now a vast and desolate space covered with ice, rock and debris. The helicopter dropped them and their guide at the small settlement of Kyanjin Gompa at the very top of the valley, and from there they walked down to the valley floor.

“It was bad. I can’t lie. I felt very focused as I left the US to find my mom. But when I flew over the valley and saw the devastation, I felt pretty broken,” said Habash.

They had pieced together her mother’s movements from survivors’ accounts, and Kyanjin Gompa was where they could last place her. “We know she was there at 9am and that she set off to walk down to Langtang village.”

According to Dorothea Stumm, a glaciologist at the Nepal-based International Centre for Integrated Mountain Development, a massive hanging glacier cracked when the earthquake struck at 11.56am. The ice formed a cloud that gathered snow and rocks and then funnelled down the mountain, burying the village, and creating an enormous pressurised blast.

“It was like an atomic bomb going off,” says Harris. He estimates the devastated area as a mile and a half long and half a mile wide. The Nepalese army estimates that the ice and rock is 30m deep. “It flattened trees up the mountain on the other side of the valley,” said Habash. “You can see where it stripped bark from the trunks of the trees.”

It was Habash who had urged her mother to trek the Langtang region. They had hiked the Annapurna circuit together when she was still a teenager and she had returned, aged 19, to the Langtang area. (Nepal’s third most popular trekking area, it is visited by 20,000 foreign tourists every year.) She had teamed up with a woman she met in a hostel in Kathmandu, and had loved both the landscape and the people. “It starts out as regular valley but you keep going up and then you see these immense snow-capped peaks.”

On her third day of searching, she met a Nepalese man who was searching for his mother and father. “We hiked with him for a bit and then sat down and I started asking him questions and he told me that he was 43 and had four children and I suddenly realised I knew him. I took off my hat and my sunglasses and said, ‘Do you remember me? I’m Yasmine.’ And he said, ‘Yasmine!’”

His name was Phinjo Tamang and in 1995, she had stayed with him in a settlement below Langtang and walked the trail up to the village with two of his four children. She also discovered through talking to him that her former companion, with whom she had lost touch – “it was before the age of Facebook” – had been sponsoring his son Chewang’s education. “It was so incredible. To be reunited with Phinjo, and that he was alive, and that he, too, was there looking for his mother and father. I really wanted to believe it was some sort of sign.”

Facebook Twitter Pinterest Langtang village before the second Nepal earthquake hit. Photograph: REX/Shutterstock

Phinjo Tamang had just arrived from Langtang when we visited him and his family in Kathmandu last week. Habash and Harris had bought clothes and camping equipment that people in their home town of Juneau, Alaska, had donated, and photos of the family that Habash had taken on her trek through the valley 11 years ago. They are now living in a small tent in the overcrowded grounds of a monastery, along with 350 other survivors of the Langtang valley. They have nowhere else to go. And no idea if they will ever be able to return to the valley in which their family – they are Tamang people, originally from Tibet – have lived for hundreds of years.

Phinjo Tamang had been walking from his village of Thyangshap, he told me, where his wife and one of his sons were, up to Langtang where his parents lived, when the earthquake struck.

“There was a huge noise like thunder. I heard it first and then I felt the earth shake and I saw these huge pieces of ice fall down and then the air was filled by what looked like smoke. You couldn’t see sunshine. I panicked. I didn’t know which way to go. Should I go up and try and find my parents? Or down and try to find my wife and son? I am too confused. I get to the avalanche and I can’t believe my eyes. The village is gone. I realise my parents are dead. Everyone is dead.

“I turn round and start running down to find my wife and son. I’m running but then I see two people in the ice. They’re alive. One of them is a German man. He is actually in the ice and I dig him out and then I run down to Thyangshap but there is no more Thyangshap. It’s gone. But I found my wife and son. My wife was bleeding from the head. She was hit by ice and wood. Our two youngest were in the village lower down. We don’t know where they are and my wife is crying and crying.”

The boys survived, but so many didn’t. Tim Gocher, the head of a small NGO, the Dolma Development Fund, which sponsors more than 1,000 children in the wider area to go to school, told me how he too visited the camp last week to try to locate missing children from Langtang. “It was incredibly depressing. We went through the list with the head of the camp, and he said in an emotionless voice, either ‘is’, meaning alive, or ‘isn’t’, meaning dead.

“It just felt pretty hopeless. We’ve had 18 children survive – luckily a lot of them were out of the village at the time – but many of them have no family left at all. And nobody knows if they’ll ever be able to return. Their families have lived there for generations. These incredible proud, generous, self-reliant people are now reduced to accepting aid. There’s been this old Tibetan lifestyle there for hundreds of years and suddenly everything’s gone.”

The stories are harrowing. Ten metres away from Phinjo Tamang and his family, I find Lakpha Tamang, 38, and her surviving daughter, Lachi. An Australian couple, David and Kate Gilson and their two children had come to see them.

They had stayed in the family’s guesthouse a week before the avalanche and they brought photos of Lakpha’s dead eight-year-old son, Duke, and her husband, that have left her in tears. Her sister Ganga Tamang, 28, told me her story.

“There was no option to run away. To the left, there was landslide, to the right there was landslide. She saw her husband struck in the head by a rock. And then she fell down and cut her head open. And then she saw her son’s body being carried by the wind. She rushed to try to grab him but I grabbed her hair and stopped her.”

Their older sister, Gaki, and her husband had also died, as well as Ganga’s husband and son, and their father. Their mother, they found out later, had survived but died while she was being airlifted out by helicopter.

“It is only us left there, three women and three children. We had the funeral for Duke there. We burned him. Lakpha, she couldn’t control herself. She was falling here and falling there. Her husband, he was the one who used to feed the family, and her son… he was part of her body.”

When I ask Ganga about the children who have been orphaned by the disaster, she turns to a sweet-faced boy, 13-year-old Tenzing Tamang, sitting in the entrance to the tent eating a plate of rice. “This is one. This is Gaki’s son. She is dead. His father is dead. There is only us.”

Facebook Twitter Pinterest Soldiers search for bodies after a massive avalanche overwhelmed Langtang. Photograph: Reuters

People from the surrounding villages had come to Langtang the day before for a funeral ceremony, Ganga Tamang explained, and many had stayed to visit relatives afterwards.

Austin Lord, 30, who is an American Fulbright scholar doing research for his anthropology PhD in Nepal and has spent many months in the area, had been in the village that night with his family, who were visiting Nepal for the first time.

They attended the ghewa – a Tibetan Buddhist ceremony held 49 days after someone has died, when it is believed their soul leaves bardo, a liminal state. “There were about 300 people singing through to six in the morning. It’s a funerary rite specific to this Tamang culture and I have a video from it that’s so poignant to look at now. It’s incredibly emotional even talking about it now. It’s so new and overwhelming what’s happened, and the music is so haunting, and so many of those people are now gone. It’s a true outpouring of emotion. People believe it’s during that stage of reincarnation that the souls enter another body.”

Lord and his family left the village ahead of schedule. “We were meant to be there that morning, but we left early. My family had gone ahead and I was talking to a hotel owner in the next village, which is where I’ve been researching a hydropower project, when the earthquake struck.

“I was grabbed by the hotel owner and we ran outside and it was just incredible. There were landslides coming down in all directions. And the air pressure from above was incredible. It was the most terrifying moment of my life.”

The next days, before they were evacuated, were chaotic and frightening, with aftershocks and landslides and locals trying to get their injured children aboard helicopters that had been sent to rescue western tourists.

Since then, however, he said that loss had united them all, foreigners and locals. He has been working with a group of volunteers to get relief and aid all over Rasuwa, the administrative district. Lord said that he “will forever be tied to this community. It’s incredibly emotional. To see such grief and loss is just overwhelming.”

And Yasmine Habash said she now felt “bonded” to Phinjo Tamang and his family and planned to use the money that she has raised to help support the survivors.

No one knows if Langtang will ever rise again. The threat of avalanches and landslides is likely to remain for months, if not years to come. In the meantime, Lord said: “We’re just doing what everyone else is doing: we’re all just trying to help in whatever way we can.”

If you have a story about Langtang, please contact carole.cadwalladr@theguardian.com. To help the people of Langtang, you can donate money to The Dolma Development Fund, or Rasuwa Relief