North Korea's last nuclear test had the energy of 10 Nagasaki bombs and was so powerful it moved a MOUNTAIN
Scientists have used satellite imagery to discover that a nuclear test in North Korea was so powerful it literally moved a mountain.
The explosion, which happened in September 2017, occurred at the rogue state's nuclear testing site, known as Punggye-ri and hidden inside Mt. Mantap.
Seismic sensors registered the effects of the nuclear test twice, firstly as a 6.3 magnitude earthquake which was shortly followed by a 4.1 magnitude quake.
Researchers estimate that the strength of the explosion was about 120 to 304 kilotons, or ten times the power of the bomb that was dropped on Nagasaki.
Satellite imagery revealed the mountain moved south by around 11.5 feet (3.5 meters) and shrank by 1.6 feet (0.5 m), they say.
Experts also saw signs that the huge explosion may have caused the subterranean labyrinth of tunnels to collapse, sparking fears over the mountain's stability.
This was the fifth test conducted at the site and scientists are concerned that this structural damage could unleash an environmental catastrophe.
Scientists have used satellite imagery to discover that a nuclear test in North Korea was so powerful it literally moved a mountain. The explosion from September 2017 occurred at North Korea's nuclear testing site hidden inside Mt. Mantap (mountain pictured here in January 2016)
The mountain could be on the brink of dramatic failure, according to an international team of geophysicists led by Nanyang Technological University in Singapore.
They used satellite imagery taken from the German TerraSar-X and Japan's ALOS-2 satellites to study the affects of the nuclear explosion on the mountain.
The inside of the peak has been so damaged by the repeated tests that it has been reduced to 'fragile fragments', they say.
They used a method known as 'synthetic aperture radar', which sends waves of electromagnetic radiation to Earth and measures what bounces back, to make the discovery.
Before and after pictures revealed the mountain's dramatic shift 11.5 feet (3.5 meters) to the south, as well its height shrinking by 1.6 feet (0.5 m).
In the study, its authors write: 'On 3 September, 2017, two seismic events separated by ~8.5 min were detected in the North Korea's Punggye-ri nuclear test site.
'Soon thereafter, North Korea's state media reported the successful firing of a two-stage thermonuclear bomb test.
'We determined the complete surface displacement field of up to 3.5 m of divergent horizontal motion with 0.5 m of subsidence associated with North Korea’s largest underground nuclear test using satellite radar imagery.'
Images from a couple of weeks ago show the nuclear test facility at the South Support area at Punggy-ri. This has housed five of the nine nuclear tests that have occurred worldwide Since the United Nations adopted the Comprehensive Nuclear-Test-Ban Treaty in 1996
Satellite images taken in April 2017 show the mountainous landscape around the nuclear test site and the different portals leading to a labyrinth of tunnels
1) Bomb explodes and sends seismic waves through Mt Mantap 2) As the waves travel rebound in a process known as 'slapdown', the summit collapses sightly 3) 8.5 minutes after the explosion an earthquake is triggered and 4) Both events cause the mountain to move south
Mt Mantap is located in the north east of the secretive state's territory and is the clandestine home of its nuclear testing programme.
A number of detonations have occurred at the Punggye-ri base inside the mountain in recent years.
The latest, on September 3, 2017, may have been the final one.
Since the United Nations General Assembly adopted the Comprehensive Nuclear-Test-Ban Treaty in 1996, nine nuclear tests have taken place.
Six of these were by North Korea, five of which were at its Mt Mantap facility.
According to scientists, the inside of the peak has been damaged by the repeated tests that it has been reduced to 'fragile fragments'. Using satellite pictures, scientists saw was the shift of an entire mountain 11.5 feet (3.5 meters) south and shrank by 1.6 feet (0.5 m)
When the nuclear bomb went off last year, speculation from scientists reported by the South China Morning Post explained the dramatic implications of 'tired mountain syndrome'.
Wang Naiyan, a former chairman of the China Nuclear Society and a researcher on China's own nuclear weapons programme, said he feared just one more test could 'take the mountain's roof off', sparking a toxic radiation drift across the region.
'We call it 'taking the roof off'. If the mountain collapses and the hole is exposed, it will let out many bad things.
According to the South Korea's Yonhap news agency, Seoul's National Intelligence Service said it was the fifth blast the North had conducted in the same No 2 tunnel at the Punggye-ri test site, and it was 'likely to have collapsed'.
The research published this week corroborates this theory.
The impact of a single nuclear bomb can be devastating. North Korea have been testing these weapons as well as ballistic missiles (pictured) for some time
The Punggye-ri site inside Mt Mantap in North Korea has been subjected to five different bombs. Political enigma and North Korean ruler Kim Jong-un announced the decommissioning of Punggye-ri earlier this year
Did Kim promise to end missile launches because his test site was ALREADY out of action?
Kim Jong-un only agreed to freeze his missile tests because his underground nuclear test site has collapsed, Chinese experts suggested on Wednesday.
The dictator announced on Saturday he would halt nuke trials and intercontinental missile launches and also vowed to dismantle the atomic facility at Punggye-ri in the country's north east to 'transparently guarantee' the end of testing.
But the surprise announcement comes after reports last year of major earthquakes and landslides in the mountainous area in the wake of five test blasts carried out by the secretive state in recent years.
The dictator announced on Saturday he would halt nuke trials and intercontinental missile launches. But doubt now surrounds the honesty of this claim after evidence revealed the test site was already damaged, including by landslides depicted on this map
According to the South China Morning Post, two groups of Chinese experts say the military facility has collapsed 'putting China and other nearby nations at unprecedented risk of radioactive exposure'.
One of the experts said this could be the real reason behind Kim Jong-un's decision to end his missile and nuclear trials.
The tyrant had claimed that the freeze was because he had now successfully developed the country's arsenal, including miniaturizing warheads to fit them on to rockets.
But Wen Lianxing, from the University of Science and Technology of China in Hefei, and his researchers have concluded that a major collapse took place at Kim's atomic site after the country's sixth nuclear test in September.
At the time, Japan estimated that the blast was measured at 120 kilotons, eight times the size of the US device that destroyed Hiroshima in 1945.
Satellite images appeared to show multiple landslides in the wake of the hydrogen bomb blast, with green mountains reduced to muddy hillsides.
Weeks later, unverified reports emerged that up to 200 workers may have been killed during the construction of a new tunnel at the site. Three small earthquakes then hit nearby regions, it is claimed.
A map showing the atomic facility at Punggye-ri and piles of dumped material that show the construction of a tunnel, where dozens of workers are thought to have died after the structure collapsed
North Korean ruler Kim Jong-un announced the decommissioning of Punggye-ri earlier this year.
It was well received in the media and by politicians worldwide, but the gesture could have been made out of necessity rather than desire.
The surrounding areas around the mountain has been reported to been plagued with landslides and repeated earthquakes following years of nuclear explosions.
Some suggest that it's lack of suitability for future tests has led to the closure of the mountain site, rather than a sudden change of heart by Pyongyang.
With several tunnels in and out of the summit, there have been different ideas as to how to secure the vast amounts of nuclear waste contained at Punggye-ri.
One theory suggests using explosives to seal the entrances to the three tunnels that have been drilled into the mountain.
The obvious risk here is that the tremors could trigger a chain reaction, causing the site to collapse and releasing a concoction of radioactivity in to the air.
Another idea is a long-winded process which involves burying the entire site in sand and lime.
The full findings of the study were published in the journal Science.
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