The South Korean government has convened an emergency meeting over the issue, YTN television reported.
North Korea is expected to make a statement concerning the earthquake at 4:00 AM GMT.
South Korea's weather service reported that the 4.2 magnitude earthquake was of an "artificial nature." US seismologists say that the epicenter was located in Pekam county, in Yangkang province.
South Korean sources reported that the earthquake occurred near the town of Kilchu.
In 2003, Pyongyang withdrew from the international Nuclear Non-Proliferation Treaty (NPT), a deal that was intended to prevent the spread of nuclear weapons manufacture and possible use.
In 2005, North Korea declared itself a nuclear power, and conducted several nuclear weapons tests, sparking concerns in the international community, particularly in neighboring South Korea. Almost four years later, Pyongyang tested additional nuclear weapons.
The official data on the country's nuclear program has not been released, and research on the issue is based on external observations and reports made by North Korean authorities.
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