China fears N. Korean quake an ‘explosion’

The earthquake was detected in Kilju county, where North Korea’s known Punggyeri nuclear site is located.

istered as earthquakes of magnitude 4.3 or above. The last test on 3 September registered as a 6.3 magnitude quake. A secondary tremor detected after that test could have been caused by the collapse of a tunnel at the mountainous site, experts said at the time. Satellite photos of the area after the 3 September quake showed numerous landslides apparently caused by the massive blast, which North Korea said was an advanced hydrogen bomb.

The head of the nuclear test monitoring agency CTBTO said on Saturday that analysts were “looking at unusual seismic activity of a much smaller magnitude” than the 3 September test in North Korea.

“Two # Seismic Events! 0829UTC & much smaller @ 0443UTC unlikely Man-made! Similar to ”collapse“event 8.5 mins after DPRK6! Analysis ongoing,” CTBTO Executive Secretary Lassina Zerbo said in a Twitter post, referring to 3 September test. Russia’s emergency ministry says background radiation in nearby Vladivostok was within the natural range.

The US Geological Survey said it could not conclusively confirm whether the quake, which it measured at magnitude 3.5, was manmade or natural.

“The depth is poorly constrained and has been held to five km by the seismologist,” USGS said. “The Air Force Technical Applications Center (AFTAC) is the sole organization in the US federal government whose mission is to detect and report technical data from foreign nuclear explosions.”

Tensions have continued to rise around the Korean peninsula since Pyongyang carried out its sixth nuclear test, prompting a new round of UN sanctions.

North Korea’s Foreign Minister Ri Yong Ho, currently in New York for a United Nations meeting, warned on Thursday that Kim could consider a hydrogen bomb test of an unprecedented scale over the Pacific.

US President Donald Trump called the North Korean leader a “madman” on Friday, a day after Kim dubbed him a “mentally deranged US dotard” who would face the “highest level of hard-line countermeasure in history”.

North Korea’s nuclear tests to date have all been underground, and experts say an atmospheric test, which would be the first since one by China in 1980, would be proof of the success of its weapons program.