“Artificial”?
That doesn’t sound good.
USGS is calling it an explosion.
http://earthquake.usgs.gov/earthquakes/eventpage/us10006n8a#executive
Earlier today a post at 38 North Blog said new activity has been detected at Punggye Ri
http://38north.org/2016/09/punggye090816/
From Drudge Quake Sheet:
5.3
Explosion 15km ENE of Sungjibaegam, North Korea
2016-09-09 00:30:01 (UTC)
0.0 km
Man caused earthquake