A magnitude 3.4 tremor struck Saturday close to North Korea’s nuclear test site, though South Korea’s weather agency said it was a natural earthquake.
The tremor occurred at 4.29 p.m. China time and had a depth of zero meters, the China Earthquake Networks Center said in a statement, adding it was a suspected blast. South Korea’s weather agency said in a statement on its website that the tremor was a natural occurrence, though it hit close to the area where North Korea conducts nuclear tests.
The United States Geological Survey put the quake’s magnitude at 3.5 and its depth at 5 kilometers.
“This event occurred in the area of the previous North Korean Nuclear tests,” the USGS said on its website. “We cannot conclusively confirm at this time the nature (natural or human-made) of the event.”
The earthquake-monitoring agency in neighboring China said it suspected that the North Korean quake, which occurred at 3:59 p.m. local time, was caused by an explosion, though the magnitude was significantly lower than a previous nuclear test earlier this month. The USGS estimated the depth of Saturday’s quake to be five kilometers (three miles).
Nuclear proliferation watchdog CTBTO said the quake was unlikely to have been man-made, report The Washington Post.
North Korea detonated its sixth and most powerful nuclear weapon earlier this month at its underground Punggye-ri site northeast of Pyongyang, causing a quake with a magnitude of around 6.3. The move escalated tensions with the U.S. and North Korea’s neighbors, and this week its foreign minister said the regime’s options included testing a hydrogen bomb in the Pacific Ocean.
There have been concerns about the stability of the nuclear test site since the Sept. 3 test. Website 38 North said satellite imagery taken after that test appeared to show landslides atop the site that were more numerous and widespread than after the previous five tests.
The site, run by the U.S.-Korea Institute at Johns Hopkins University’s School of Advanced International Studies, added the bomb’s 250-kiloton yield was close to what it previously determined was the maximum that could be contained by the test site.
The Sept. 3 detonation followed two intercontinental ballistic missile launches in July that brought Kim Jong Un’s isolated regime a step closer to achieving its aim of being able to deploy a nuclear warhead over the continental U.S.
On Thursday, North Korea struck back at U.S. President Donald Trump’s threats to destroy it, with Kim warning of the “highest level of hard-line countermeasure in history” and his foreign minister suggesting that could include testing a hydrogen bomb in the Pacific Ocean.
His comments came after Trump ordered new sanctions on individuals, companies and banks doing business with North Korea as he sought to further isolate the regime and increase economic pressure for it to curb its weapons programs.
North Korea’s state media issued a statement Saturday from the National Peace Committee of Korea describing Trump as “wicked” and “a rabid dog.”
U.S. analysts now estimate that North Korea may have as many as 60 nuclear weapons, according to a Washington Post report. That’s in addition to cyberwarfare capabilities, a biological weapons research program and a chemical weapons stockpile. It also has a vast array of conventional artillery aimed at Seoul.