TOKYO -- There were signs of unusual seismic activity around North Korea's main nuclear test site Wednesday morning, sparking fears that Pyongyang had carried out the detonation of another device there.
Earthquake agencies in China, Japan and the United States all recorded seismic activity in the north-eastern corner of North Korea at about 10:30 a.m. local time Wednesday, with the U.S. Geological Service reporting a shallow 5.1-magnitude quake about 10 miles from Sungjibaegam, about 20 miles from the facility where North Korea has carried out its three previous nuclear tests.
Japan's Meteorological Agency said that it appeared to be some kind of artificial explosion and that the waveform was very similar to the ones detected at the nuclear tests in the past, public broadcaster NHK reported.
In Seoul, the National Intelligence Service said it was investigating the quake, while the presidential Blue House called an emergency national security council meeting. The cabinet in Tokyo was also holding an urgent meeting of security officials Wednesday morning.
North Korea has conducted three nuclear tests since 2006 but only one during Kim Jong Un's reign, in February 2013.