Seoul: Small quake in North Korea likely due to mining blast
https://phys.org/news/2019-03-seoul-small-quake-north-korea.html
The official says the quake was man-made and likely caused by an intentional blast in a coal mine.
"Our map data shows the locations of mines across North Korea, and we also detected soundwaves, proving that this quake was caused by an explosion," he said. He didn't want to be named, citing office rules.
