0.5 kt North Korean Test? Comparison With Other Tests

http://www.gwu.edu/~nsarchiv/NSAEBB/NSAEBB200/index.htm

Thus, on August 16, 1997 a seismic signal from the vicinity of Novaya Zemlya registered at 3.2 on the Richter scale--consistent with a very small blast of between 0.1 and 1.0 kiloton, which might indicate scaled-down tests of a warhead primary.

http://www.cnn.com/WORLD/asiapcf/9805/30/pakistan.nuclear/index.html?eref=sitese arch
[Pakistan Test]
U.S. officials say the blast registered about 4.6 on the Richter scale, roughly equivalent to Thursday's blast...Preliminary analysis of the data suggests a yield in Thursday's test of six kilotons...

http://www.fas.org/nuke/control/ctbt/news/980521-ctbt.htm

UNIVERSITY OF ARIZONA SEISMOLOGIST TERRY WALLACE HAS BEEN TRACKING SUCH EVENTS FOR 25 YEARS. HE SAYS A ONE KILOTON NUCLEAR TEST SHAKES THE EARTH ABOUT THE SAME AS AN EARTHQUAKE MEASURING 4-POINT-ONE ON THE RICHTER SCALE.