Full Title: North Korea is hit by 'artificial' 2.1-magnitude earthquake after 'mine explosion' amid claims Pyongyang is reviving a nuclear launch site An earthquake in a mining town in North Korea was caused by 'artificial activity', it has been claimed. The 2.1-magnitude tremor was reported in the town of Pyonggang near the border with South Korea around Thursday lunchtime. Meteorology experts in the South said the quake was likely to be caused by a mine explosion.