The story of how Sepulveda and 32 colleagues - universally known as "Los 33" - survived for 69 days underground, before being hauled one by one to the surface in an unprecedented triumph of engineering, captured the imagination of the world.
Their tale is being told in a Hollywood film, with Antonio Banderas starring as Sepulveda and Juliette Binoche as the sister of another miner, Dario Segovia. Filming has finished, with the premiere due at the end of this year. And this week came the publication of their book, Deep Down Dark, which tells the story of the men and their ordeal 800m beneath the desert.
"We thought at times we would never get out," said Juan Illanes, 56, another of the miners. "It seemed impossible. But then, once it became clear that we might make it, we thought about how best to tell our story."
The men decided to all work together with an author to publish one volume - "the genuine, truthful version", said Illanes proudly.
Hector Tobar, a Los Angeles-based author of Guatemalan origin was chosen for the task, and one by one they met Tobar to give their version of events.
All 33 of the men will share the profits equally, said Illanes - even Carlos Mamani, their Bolivian colleague, who had been in the mine for only a few days when he was trapped with the others.
"But we soon had him singing the Chilean national anthem with us," said Illanes with a laugh.
The men are open about their struggle to come to terms with their new-found fame. In the four years since the accident, many have suffered from psychological problems, while others have sought refuge in alcohol. Yonni Barrios, whose wife and mistress of a decade both turned up at the mine to stand by their man, divorced his wife of 28 years and is now married to his mistress. Barrios, 54, like many of the older miners, has spent 30 years working in the mines and is now suffering from the terminal lung condition silicosis.
Alex Vega was at the birth of his three children - but has no memory of it. He is seeing a psychiatrist, and taking medication.
Edison Pena, 38, known as "the runner", who would jog for miles underground during his entrapment, ran the New York marathon three weeks after emerging from the mine and appeared on United States chat shows, but has since been admitted to rehab for psychiatric care and substance abuse. He returned to New York to run the race the following year a subdued and sombre figure.
"I'm here despite the fact that I've fallen down to show that I've risen up," he said at the time. "I don't really want to go into depth about the challenges that I faced, but suffice to say, I have got help and declared a truce with the problems I've had."
Illanes sympathises with the problems his colleagues have faced.
"It's very hard to make good decisions about all this," he said. "We had no idea what was awaiting us. I know it sounds impossible to believe now, but when the rock fell my immediate concern was for my employer.
"I thought, 'I hope this doesn't end the company, because if I lose my job, what will I do then?'
"I was so limited in my mind I couldn't think beyond that. And it wasn't until Laurence Golborne, the Mining Minister, spoke to us that we realised what was happening. He used the loudspeaker system they brought in, and told us: 'You guys cannot even imagine the circus that is going on above your heads'."
As the men waited for the tunnels to be dug so that the rocket-shaped capsules could be lowered to their cave for the rescue, a mini city mushroomed on the surface. Nicknamed Camp Hope, the desert community drew all the families of the men, plus thousands of reporters and television crews.
As they were lifted to the surface, in images beamed around the world, Chile's then-president Sebastian Pinera was at the tunnel to hug the ecstatic families and their men.
Sepulveda, the wisecracking extrovert who became most high-profile of the group, emerged bouncing from the tunnel, whipping up the crowd with whoops of joy and chants of "Viva Chile!"
But over the next four years, his ardour would cool.
"Chile is known worldwide thanks to us," he said. "It has a huge debt to us. And yet we feel that we have not been properly looked after by our Government."
The men received a one-off payment of US$14,500 from a local businessman and were showered with gifts including a motorcycle and a free trip to Disneyland. All 33 were promised a pension, but in the end only the 14 oldest miners were given one. And in August last year a prosecutor in the northern region of Atacama decided to bring no charges against the mine owners, Alejandro Bohn and Marcelo Kemmeny, or Chile's Mining Ministry's regulatory unit.
"It's an irresponsible judgment, and just not serious," Sepulveda said. "We're not asking for money from them. Just justice. We want to make sure that this never happens again."
Sepulveda feels strongly that the men have been short-changed from the ordeal, while others have profited - politically or financially.
Yet he is perhaps one of the better-off of Los 33. A father of three, whose wife Katty manages his affairs, he now works for a building company, but also gives motivational talks, and plans on writing his own book. He would consider going back to the mine, but hopes it doesn't come to that. Some of his colleagues have gone back - Illanes and Mamani among them, working above ground as supervisors. Some are working underground. This week's meeting in Copiapo, which was attended by the majority of Los 33, was to discuss how to ramp up their civil case for damages against the Government - under Chilean law they have only 12 months left before the process will expire.
"I understand the system far better now than I did back then," said Sepulveda. "So many people made money from us. And they didn't pay what they should have."
Illanes, whose 20-year career in the mines was preceded by years as a soldier, agrees that they could have handled the situation better.
But he is not despondent, and is delighted to tell the stories of his life, speaking by telephone from the windswept mine where he now oversees operations.
"I remember we were invited to Manchester, to visit Old Trafford," he recalled. "It was fabulous - totally unforgettable. We were taken on a bit of a tour of the city, and we ended up in the Chinese district of the city. This woman came over, and she looked at me, and said something - I have no idea of her exact words, but she said 'Chile?' and I nodded.
"And then she said some more things I didn't understand, but said 'Miner?' And I nodded. And then she had like this emotional explosion - she was so happy, and hugged us, and was so pleased for us.
"It was amazing to have this connection with someone from such a different world."
With the book, he says, he hopes to tell their version of events for history. He hopes to bring about some closure - and also make a bit of money to help his wife Carmen and 25-year-old son. So it's been tough, but also beautiful."
