On September 2017 North Korea had it sixth nuclear test that was so powerful, it is still causing earthquakes more than a year later. That nuclear test was North Korea’s most powerful to date. The initial blast caused a 6.3-magnitude tremor.
For more info, please read the original article by CNN:
https://www.cnn.com/2019/01/01/asia/north-korea-earthquake-intl/index.html
