North Korea’s nuclear test site

Nuclear tests: Estimated yields (1kt = 1,000 tons of TNT) Quake magnitude 


1 Oct 2006: 1kt 4.3
2 May 2009: 2-5kt 4.7
3 Feb 2013: 6-14kt 5.1
4 Jan 2016: 7-10kt 5.1
5 Sep 2016: 20-30kt 5.3 
6 Sep 2017: 120kt 6.3
500m 550yds

Mount Mantap
Punggye-ri command centre


CHINA
RUSSIA
NORTH KOREA
SOUTH KOREA
P’yongyang 
Hamgyong Mts
Punggye-ri
Demilitarized Zone (DMZ)
100km 60 miles

Tunnel: 3m wide x 3m high
700 metres
Nuclear device: Placed at end of tunnel
Blast intended to be absorbed within area defined by first four bulkheads
Tunnel entrance

TUNNEL LAYOUT: Based on tunnel featured in propaganda film of 2009 test. Shaped like fish-hook, similar to design used by Pakistan

Sharp corners, and several dead ends used as debris traps, help deflect and absorb blast

Sand, gravel or other materials can be mixed with concrete to plug segments of tunnel to further contain explosion and prevent ejecta from escaping into atmosphere

1 Blast doors               1 Debris trap

Sources: 38 North, Bulletin of Atomic Scientists, USGS
Picture: Google Earth           © GRAPHIC NEWS