China’s environment ministry started emergency radiation monitoring along its border regions in northeastern China on Friday morning after North Korean state media confirmed it carried out a fifth nuclear test on Friday.
“Artificial seismic waves” from a 5.3-magnitude quake were detected near North Korea’s Punggye-ri nuclear test site, a South Korean official said.
Pyongyang celebrates Foundation Day on Friday, which marks the anniversary of the founding of the nation in 1948.
North Korean state media reported that the test had not caused any adverse effect on the surrounding environment and no radioactive materials had leaked from the underground test site.
The successful nuclear test had placed North Korea in a “strategic position”, the report said.
Data collected by the National Radiation Environmental Data Evaluation System, checked at noon on Friday – hours after the nuclear test – showed that not one of the three observation centres in Jilin province and the three in Liaoning province, located close to the border with North Korea, had detected any abnormal signs of radiation.
Chinese residents living near the border said on social media that they had felt a strong tremor similar in size to when North Korea conducted a nuclear test in January.
A Weibo user named “Scriptwriter Little Six” living in Yanbian Korean Autonomous Prefecture, on the border with North Korea, said he was awakened by a quake at around 8.30am, which sent furniture crashing and shattered windows in his home
He said he was so scared that he immediately jumped out of bed and ran out of his house.
Another Weibo user, living in Changbai Korean Autonomous County, in Jilin province, said she had felt a clear tremor this morning and her first thought was that North Korea had conducted another nuclear test.
“Because this place is not above a seismic belt and has no oil reserves, it must be another nuclear test by [North Korean leader] Kim Jong-un,” she wrote.
Friday’s earthquake is the largest of the four past tremors to have been caused as a result of Pyongyang’s nuclear tests.
Previous artificial earthquakes in the same area have all been confirmed as nuclear tests.
A 4.8-magnitude quake was reported when Pyongyang conducted its fourth test in January.