South Korean agencies reported a 5.0 magnitude earthquake near the country's nuclear testing site on Friday morning, the Associated Press reports.
Yonhap news agency in South Korea said the quake was "artificial," and that previous artificial quakes of that strength had been nuclear tests. Officials in Seoul have called for an emergency National Security Council meeting.
The earthquake was caused by "possible explosion," according to the U.S. Geological Survey, but it also said it could not "determine what type of explosion it may be, whether nuclear or any other possible type."
Possible explosion, located near the location where North Korea has detonated nuclear explosions in the past. If this is indeed an explosion, the USGS National Earthquake Information Center cannot determine what type of explosion it may be, whether nuclear or any other possible type
North Korea conducted its fourth nuclear test in January, resulting in tough sanctions from the United Nations.
Reuters reported that suspicion of a test had been looming for months after the United States blacklisted Kim Jung Un for human rights abuses in July. Satellite images from a U.S.-based North Korea monitoring project showed "high level of activity" near the testing area two months ago.