North Korean quake ‘was probably not due to nuclear blast’

Experts ease fears following 3.4-magnitude earthquake near nuclear test site

People watch a television news screen showing a map of the epicenter of an earthquake in North Korea, at a railway station in Seoul on September 23rd. Photograph: Yeon Je Jung/AFP/Getty Images

People watch a television news screen showing a map of the epicenter of an earthquake in North Korea, at a railway station in Seoul on September 23rd. Photograph: Yeon Je Jung/AFP/Getty Images


A small earthquake near North Korea’s nuclear test site on Saturday was probably not man-made, the nuclear proliferation watchdog and South Korean officials said, easing fears that Pyongyang had exploded another nuclear bomb just weeks after its last one.

The China Earthquake Administration said the quake was not a nuclear explosion and had the characteristics of a natural tremor. The administration had said earlier the magnitude 3.4 quake detected at 9.29am Irish time was a “suspected explosion”.

The CTBTO, or Comprehensive Test-Ban Treaty Organisation, which monitors nuclear tests, and officials of the South Korean meteorological agency said they believed it was a natural quake.

The Pentagon and the US state department did not immediately respond to requests for comment

A US intelligence official and US-based non-governmental experts said their initial assessment was that the quake was either natural or connected to North Korea’s latest and largest nuclear test on September 3rd, and not caused by a new nuclear test.

“It seems likely that these small tremors are related to the shifts in the ground due to the recent large test,” said David Wright, of the Union of Concerned Scientists in the US.

The seismic activity came just hours before North Korea’s foreign minister Ri Yong-ho, who warned on Thursday that North Korea could consider a hydrogen bomb test of an unprecedented scale over the Pacific, was due to address the UN General Assembly in New York.

Ri did not respond when asked by reporters whether North Korea had conducted a new nuclear test.

A US government intelligence analyst said the events could have been a collapse of tunnels damaged by North Korea’s previous nuclear test, but was more likely a small earthquake.

An official of South Korea’s Meteorological Agency said acoustic waves should be detected in the event of a man-made earthquake.

“In this case we saw none. So as of now, we are categorising this as a natural earthquake.”

The earthquake, which South Korea’s Meteorological Agency put at magnitude 3.0, was detected 49km from Kilju in North Hamgyong province, where North Korea’s known Punggye-ri nuclear site is located, the official said.

All of North Korea’s six nuclear tests registered as earthquakes of magnitude 4.3 or above. The last test registered as a 6.3-magnitude quake.

Satellite photos of the area after the September 3rd quake showed numerous landslides apparently caused by the massive blast, which North Korea said was an advanced hydrogen bomb.

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


The US Geological Survey (USGS) said it could not conclusively confirm whether the quake, which it measured at magnitude 3.5, was man-made or natural.

“The depth is poorly constrained and has been held to 5km by the seismologist,” the USGS said.

There was no immediate reaction from China’s foreign ministry, but the news was widely reported by Chinese state media outlets and on social media.

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

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 hardline countermeasure in history”.

Kim was responding to a speech by Trump at the UN General Assembly in which Trump said the US would “totally destroy” North Korea if it threatened the US or its allies.

On Thursday, Trump announced new US sanctions that he said allowed the targeting of companies and institutions that finance and facilitate trade with North Korea.

Earlier on Saturday, China said it will limit exports to North Korea of refined petroleum products from October 1st and ban exports of condensates and liquefied natural gas immediately to comply with the latest UN sanctions. It will also ban imports of textiles from North Korea.

North Korea has launched dozens of missiles this year, several of them flying over Japan, as it accelerates a weapons programme aimed at enabling it to target the US with a nuclear-tipped missile.