A 5.1 magnitude earthquake was detected in North Korea Wednesday (Jan 6) near a known nuclear test site in the country.

According to the United States Geological Survey (USGS), the quake hit 49 kilometres from the Punggye-ri site where the North has conducted nuclear tests in the past, triggering concerns that Pyongyang had conducted a fresh atomic explosion.

There was no immediate confirmation that a nuclear test had been carried out but China earthquake monitors reported that the earthquake was a “suspected explosion”. It occurred 10 kilometres below the surface and was registered at 9.30am local time.

“We suspect a man-made earthquake and are analysing the scale and epicentre of the quake with the geoscience and mineral resource institute of South Korea,” a Korea Meteorological Administration official told Reuters.

According to AFP, China’s earthquake monitors say that an explosion could have caused the earthquake to register.

Yonhap reported that South Korea’s foreign ministry was to hold an emergency meeting following the earthquake. The country’s presidential office said it was looking at all possibilities, including a nuclear test.

In 2013, a bomb test in the same area, near the Punggye-ri nuclear test site, registered a 5.1 magnitude tremor, which North Korea claimed was a successful nuclear detonation.

It follows South Korea media reports that North Korea appeared to have carried out a test of a submarine-launched ballistic missile last month.

South Korea’s Yonhap News Agency cited an unnamed South Korean government official as saying Pyongyang appeared to have conducted an ejection test of a submarine-launched ballistic missile (SLBM) in December, following a reported failure of such a test in November.

A South Korean military official told Reuters that North Korea continued to develop submarine-launched missile capability but expects it will take a substantial period of time for it to be able to successfully deploy such a weapon.