National geological agencies could not confirm on Saturday what caused an earthquake in North Korea at the same site where it had conducted a nuclear test.
South Korea’s weather agency said its analysis had determined that the quake’s origin was probably “natural’’, the Yonhap News Agency reported.
The agency said the quake occurred around Kilju in north-eastern North Korea, about 20 kilometres south-east of the site of a nuclear test earlier this month.
“The quake is presumed to have occurred naturally, a sound wave, which is usually generated in the event of an artificial earthquake, was not detected,’’ said an agency official.
The U.S. Geological Survey and Japan’s Meteorological Agency both detected the tremor but said they could not judge the cause.
The Norway-based geological monitoring agency said the quake was likely caused by an aftershock rather than a new nuclear blast.
“A likely explanation of the signals is an aftershock or rock failure resulting from the previous large underground nuclear test carried out on Sept. 3, the agency said.
China had reported earlier Saturday that the quake was likely caused by an explosion, raising fears that North Korea had conducted a fresh nuclear test.
Pyongyang conducted its sixth and most powerful nuclear test on Sept. 3, claiming it had tested a hydrogen bomb that could be loaded into an intercontinental ballistic missile.
Separate geological agencies had detected two artificial tremors near North Korea’s previous test site before the country touted its “perfect success’’ in a special announcement later that day.
The test provoked international condemnation and led the UN Security Council to impose fresh sanctions on North Korea.
North Korean leader Kim Jong Un has lashed out as world leaders have tightened the screws on his regime in Pyongyang over its nuclear programme and repeated missile tests.
North Korea fired a missile last week that travelled over Japan’s northern island of Hokkaido and plunged into the Pacific Ocean.
Pyongyang also launched a ballistic missile in late August that flew over the island before falling into the sea.
Japanese defence officials believe the missile has a range of up to 5,000 kilometres.
U.S. President Donald Trump and Kim also hurled insults and accusations of madness at each other earlier this week.
Trump on Tuesday told the United Nations the U.S. could “totally destroy’’ North Korea, provoking a fierce response from Pyongyang.
Kim said Trump’s “mentally deranged behaviour’’ and his threat to destroy North Korea “convinced me … that the path I chose is correct and that is the one I have to follow to the last,’’ Kim said in a statement.