Seoul: North Korea appears to have conducted a sixth nuclear test, the South's Yonhap News Agency said Sunday citing military officials, just hours after Pyongyang claimed to have developed a hydrogen bomb that could be loaded into a long-range missile.
South Korean President Moon Jae-in has convened an emergency National Security Council (NSC) meeting following the earthquake and a report by North Korean state-media that Kim Jong-un inspected a hydrogen bomb being loaded into a new intercontinental ballistic missile (ICBM) after it claimed to have made a "more developed nuke".
Soon after the tremors, the South Korean military said, "The 5.6 quake that struck North Korea was artificial, analyzing to see if it was a nuclear test."
The USGS upgraded the magnitude of the shaking caused by the nuclear test to 6.3 and added that the quake struck 55 km north northwest of Kimchaek. There were no immediate reports of damage or casualties.
USGS recorded what they described as a shallow 5.1-magnitude "mining explosion" 24 kilometres (15 miles) east northeast of Sungjibaegam in North Korea, in an updated report. "An artificial quake was detected at 12:36 pm in areas in the North Hamgyeong Province," the Korea Meteorological Administration told AFP.
Earlier, media reports said that an earthquake measuring 5.2 struck North Korea on Sunday.
Previous recent tremors in the region have been caused by nuclear tests. Since 2006, North Korea has carried out five nuclear tests, including two last year.
Jana Pursely, a USGS geophysicist, told AFP: "It`s an explosion rather than an earthquake."
Nuclear-armed Pyongyang has long sought the means to deliver an atomic warhead to the United States, its sworn enemy.
Questions remain over whether it has successfully miniaturised its weapons, and whether it has a working H-bomb, but the official Korean Central News Agency said before the quake that leader Kim Jong-Un had inspected such a device at the Nuclear Weapons Institute.
It was a "thermonuclear weapon with super explosive power made by our own efforts and technology", KCNA cited Kim as saying, and "all components of the H-bomb were 100 percent domestically made".
Pictures showed Kim in black suit examining a metal casing, with a shape akin to a peanut shell.
North Korea triggered a new ramping up of tensions in July, when it carried out two successful tests of an ICBM, the Hwasong-14, which apparently brought much of the US mainland within range.
It has since threatened to send a salvo of rockets towards the US territory of Guam, and last week fired a missile over Japan and into the Pacific, the first time time it has ever acknowledged doing so.
US President Donald Trump has warned Pyongyang that it faces "fire and fury", and that Washington`s weapons are "locked and loaded".
Trump spoke by telephone to Japan`s Prime Minister Shinzo Abe to discuss the need to "maximize pressure on North Korea" in the face of the "growing threat" it presented, according to a White House readout of the call, without specifying when it took place.
The North has repeatedly claimed that it has a thermonuclear weapon, which can be far more powerful than other nuclear devices.
(With Agency inputs)
