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The latest nuclear test triggered a series of tremors, landslide and underground cave-ins
Since 2006, North Korea has conducted all but one of its six nuclear tests in the same spot, Mount Mantap.
Officials say the mountain, situated in the Hamgyong Province, is starting to show geological changes that suggest another test could cause the ground and the top of the mountain to collapse.

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A seismologist at Columbia University’s Lamont-Doherty Earth Observatory, Paul Richards, said: “What we are seeing from North Korea looks like some kind of stress in the ground.
“In that part of the world, there were stresses in the ground, but the explosions have shaken them up.”
Director of the Korea Meteorological Administration, Nam Jae-cheol, told South Korean lawmakers that collapse is a “real possibility”.
Pyongyang’s September 3 test is considered the most powerful by officials, producing between 50 and 300 kilotons of explosive energy, compared to the bombs dropped on Hiroshima which only measured at 15 kilotons.
The test triggered a series of tremors, landslide and underground cave-ins.
The condition of Mount Mantap is known as “tired mountain syndrome”, arising from repeated underground nuclear testing which fractures rocks and creates an unstable area.
The worse case scenario is radioactive material shooting into the atmosphere after the collapse of the mountain’s top.
But some experts believe it might not happen.
Senior scientist at the Union of Concerned Scientists, Edwin Lyman, said: “While radioactive material would be released into the environment if the collapse occurred right after a test, the amount of fallout, even from a weapon in the 100 kiloton range, would likely only cause significant contamination in the vicinity of the site and perhaps a few hundred miles downwind.
“Nevertheless, any amount of radioactive contamination of the environment from North Korea’s abhorrent nuclear test program is unacceptable and would add insult to injury.”
It comes as China gave a similar warning to North Korea not to detonate another hydrogen bomb.
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North Korea has conducted all but one of its six nuclear tests in the same spot
Scientists from Beijing believe the Punggye-ri nuclear facility is unstable and that just one more explosion could blow the top off of Mount Mantap.
Zhai Mingguo, a senior Chinese geologist, said: “This is a big, sophisticated problem requiring multiple, systematic approaches.
“Our meeting is only a part of the efforts.”
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Kim Han-kwon, a professor at the Korea National Diplomatic Academy in Seoul said: “North Korea has been walking a diplomatic tightrope by taking advantage of strategic mistrust between China and Russia, but it has not been easy as Beijing has sternly responded to its nuclear and missile provocations.”
North Korea has not engaged in any missile or nuclear provocations since mid-September.
Last week it was revealed Pyongyang had written an open letter to Australian MPs asking them not to support US President Donald Trump, a move Canberra politicians showed the tough economic sanctions were working.