A group of Chinese scientists have joined their North American peers in warning that North Korea’s Punggye-ri nuclear site could be on the verge of a dangerous collapse that could send a dangerous bloom of radiation floating over the border into Northern China.

As we’ve previously reported, China has stepped up its radiation monitoring on the border after detecting unsettling seismic activity surrounding the test site. Two weeks ago, a team of American scientists warned that the mountain above Pyungge-ri appeared to be suffering from “tired mountain syndrome” - a phenomenon commonly observed around Soviet Nuclear test sites.

And now in an effort to dissuade the North from carrying out another potentially destabilizing test, the South China Morning Post is reporting that a team of Chinese geologists warned their North Korean counterparts of a potentially catastrophic collapse of an underground nuclear test site on China’s doorstep during a briefing in Beijing last month.

A day after North Korea said it detonated a hydrogen bomb at the Punggye-ri facility on Sept. 3, a senior Chinese nuclear scientist warned North Korea that future tests could blow the top off the mountain, causing a massive collapse with radiation bleeding from cracks or holes in the mountainside.

Meanwhile, a researcher studying the radioactive risk from the North Korean nuclear programme at Peking University said China could no longer tolerate another land-based explosion.

“China cannot sit and wait until the site implodes. Our instruments can detect nuclear fallout when it arrives, but it will be too late by then. There will be public panic and anger at the government for not taking action,” the researcher said.

“Maybe the North Koreans themselves have realised that the site cannot take another blow. If they still want to do it, they have to do it somewhere else.”

This could be one reason why the North hasn’t moved forward with another test, like it has repeatedly threatened to do, since then, even as North Korean Foreign Minister Ri Yong-ho announced at the United Nations that Pyongyang might consider detonating a “most powerful” hydrogen bomb over the Pacific Ocean.

The Sept. 20 briefing covered a range of issues but North Korea’s nuclear tests topped the concerns for the Chinese government, according to Zhai Mingguo, a senior Chinese geologist who helped organise the meeting.

“This is a big, sophisticated problem requiring multiple, systematic approaches. Our [meeting] is only a part of [the efforts],” he said.

The North Korea delegation was headed by Lee Doh-sik, director of the Geological Research Institute at the State Academy of Sciences.

“He is a top government geologist in North Korea, but he is not involved in the nuclear weapons programme,” said Professor Peng Peng, one of the Chinese geologists who met the delegation.

The atmosphere was reserved but friendly, according to several scientists who attended the meeting.

North Korea has conducted five of the six nuclear tests it has carried out since 2006 at Punggye-ri. The most recent blast set off low level tremors and dangerous landslides that alarmed scientists observing the site.

Should the mountain collapse, the radiation released could threaten the entire hemisphere. It could even become a global threat.