new url, 2018. http://www.ga.gov.au/scientific-topics/hazards/nuclear-monitoring Once was the case that The Australian Geological Survey Organisation maintained a nice informational page on monitoring nuclear explosions, once included a queriable database, but I can't find it anymore. An example output:

The AGSO Database of Nuclear Explosions

Test site: Miscellaneous - specify area under "comment"

Nuclear tests for the period: 1944 - 1946

Date: 16 JUL 45 
       Yield: 19
       Comments: atmospheric test

Date: 05 AUG 45 
       Yield: 13
       Comments: atmospheric test

Date: 09 AUG 45 
       Yield: 23
       Comments: atmospheric test

This is a very polite way of putting it. The Japanese appreciate politeness.