Claimed to be the worst in the world in 40 years, and the 19th worst in world history, the disaster shocked not only Turkey but also the international community.
While Turkey declared three days of mourning to show unity and sympathy with the families of the deceased miners, world leaders from dozens of countries showed an outpouring of sympathy by extending condolences and offering assistance.
The mine, operated by Soma Komur Mining Company, had previously been considered one of the safest in the country, but everything started with an explosion, causing a fire about 2,000 meters from the entrance. The fire then caused the mine to fill with toxic gas.
Turkey’s Prime Ministry Disaster and Emergency Management Presidency later said that a power distribution unit caused the fire. However, the company rejected the claim.
According to an official autopsy report released last November, most of the deaths were due to a form of poisoning where red blood cells came into contact with carbon monoxide gas.
This report concluded that toxic gas was produced by a spontaneous fire which broke out in coal dumped around a transformer.
Carbon monoxide produced by this fire met fresh air from an inlet, fuelling a greater blaze.
This spread to the mine’s third and fourth corridors causing bands, timber supports, pipes and electric cables to catch fire.
Water and other attempts to extinguish the blaze produced more deadly poisonous and suffocating gas, the report also claimed.
However, given the large size of the mine, the fire which broke out underground was not solely responsible for the 301 deaths. Poison gas and suffocation produced by the blaze was the main cause of death.
Tevfik Cucu, a miner who survived the tragedy, recalled the harrowing scene when he tolld to media.
"Smoke was everywhere. We put on our masks. People couldn`t see each other as they walked. The smoke was restricting us.
"We started out with 25-30 people; when we reached ‘the breath’ [mine entrance] there was only an unconscious friend beside me..," he said.
There were over 780 workers underground at the time of the disaster; it occurred at the same time as the miners’ shift change.
Following the accident, there have been fierce protests against the government and the operators of the coal mine.
Victims` relatives have accused the company for prioritizing production over safety. Angry families have also slammed the authorities, accusing them of insufficient inspections and operating under an inadequate legal safety framework.
According to lawyer Ali Arslan -- who represents survivors and miners’ families -- after taking over the mine in 2009, the company produced 3,500 tons of coal annually. This figure should have been 500 tons per year.
Arslan also claimed that the mine owners had 4,000 workers operating at the facility, instead of the recommended number of 2,000, and with insufficient security and safety investment.
"301 lives were lost through greed," Arslan said, speaking to Anadolu Agency last month.
Arzu Kilic, mother of the one of the dead miners, Sezai Kilic, told Anadolu Agency that her son had been told he had to resume work after only a 10-minute break. The dead man’s father, Zafer Kilic, claimed his son and other workers were put under "tremendous pressure" by subcontractors.
Recep Tayyip Erdogan, who was prime minister at the time, said in a visit to the disaster area that "no one would be able to cover up this painful incident."
"The necessary criminal and administrative investigations will be carried out, and we will be strictly monitoring them," he said.
Similarly, Deputy Prime Minister Bulent Arinc said that a thorough investigation would be conducted to find out the reasons behind the incident.
Dozens of prosecutors have been assigned to oversee post-mortem examinations.
In total, 45 are facing a range of charges connected to the Soma disaster.
Eight people, including the chief executive of the company that runs the mine, were arrested May 20 last year.
The same eight are in custody, standing trial on charges of first-degree murder. They could each face 20 to 25 years in prison if convicted on each of the 301 counts against them.
They are also facing 162 separate counts of "causing aggravated injury" which each carries a possible two-to-six year jail sentence.
A total of 12 out of the remaining 37 defendants, who have been held on remand, will stand trial for "causing multiple deaths and injuries through negligence" and may face 2 to 15 years in jail.
The remaining 25 defendants are on trial accused of "conscious negligence."
A shocking tragedy for Turkey
As Turkey marks this first anniversary, the Soma disaster, by any standards, is still a shocking tragedy for the country.
Mines and stone quarries appear to be some of the most dangerous places for Turkish workers, according to government statistics.
More than 3,000 people have died and more than 100,000 have been injured in mining accidents since 1941 in Turkey, figures from the country’s official statistics agency reveal.
According to International Labor Organization (ILO) figures, Turkey ranks first in Europe and third in the world for fatal workplace accidents.
The ILO says 18 insured laborers out of 100,000 die every year in Turkey in work-related accidents across all sectors. This is seven times greater than the EU average.
After Soma, the country took considerable steps to boost occupational safety in the mining sector.
Published on the country`s Official Gazette -- a daily printed record of legislative acts and notices -- on April 23 this year, the new occupational health and safety law came into effect.
Among the new requirements is a "shelter room" where miners can go if there is a subterranean accident.
A mining company will be banned from public tenders for two years if an accident is classified as the employer`s fault, according to the new law.
Mine companies will need to pay a 500-lira ($190) fine for each of its workers who do not have the right training to work underground.
It is expected these new measures will require greater government scrutiny of the mining sector.
"With Turkey`s new draft mining law, state-owned underground coal resources will be shared only by licensed investors," Turkey’s energy minister, Taner Yildiz, in a press conference in January.
Turkey produces around 70 million tons of coal annually, and ranks 12th in the world for coal production.
Turkey is aiming for higher use of domestic coal resources by 2023 to reduce dependence on natural gas imports, which cost around $60 billion every year.