A mountain used by North Korea for its latest underground nuclear test might be in danger of collapsing and spreading dangerous radiation across the region, according to a group of scientists in China.

A secondary seismic shock following the North's test of what is believed to be a powerful hydrogen bomb Saturday was initially interpreted as a likely collapse of a cavern in Mount Mantap at its Punggye-ri nuclear test site. But analysis of satellite imagery by the site 38 North on Tuesday found no evidence that there was a cave-in on the mountain. Satellite photos did, however, show that the test appears to have triggered landslides.

The scientists at a Chinese university, led by a geologist, who have monitored the North's activity believe all six of its nuclear tests were conducted at the same location, possibly making the mountain unstable and in danger of imploding, according to the South China Morning Post.

"We call it taking the roof off. If the mountain collapses and the hole is exposed, it will let out many bad things," a former China Nuclear Society chairman and researcher on the country's nuclear weapons program told the newspaper.

38 North said lower resolution satellite images posted on its site appear to show numerous landslides and surface disturbances in the mountain's gravel and broken rock fields. The website is a clearing house for North Korea analysis and is part of the U.S.-Korea Institute at the Johns Hopkins School of Advanced International Studies,

"There does not appear to be any evidence of a collapsed crater, as might have been suggested from the post-test tremor," according to the site.

A former North Korean diplomat who defected in 2016, Thae Yong-ho, warned this year of a possible nuclear disaster related to the test site, and said such an event could bring about the collapse of the regime.

The release of nuclear radiation could cause the North to lose control of its northern border with China and trigger a massive exodus of refugees, according to Thae.

The North tested what it claims was a miniaturized hydrogen bomb capable of fitting atop an intercontinental ballistic missile. Observers have estimated the explosion was about six times more powerful than the North's previous test as it seeks to acquire nuclear weapons capable of striking major American cities.

It follows five previous nuclear tests and a series of missile launches this year that included an ICBM.

The test again ratcheted up tensions with the U.S. and its allies in the regime, which are working to stop the North's burgeoning nuclear program through sanctions and diplomacy.