[Brett66]

Yes, seismographs would have easily detected this if it happened.

[MHGinTN]

I seem to recall a brief news blurb from the clinton era that posed the question 'Was the erquake in East asia a secret nuclear test?' ... the Chinese tested the friend's weapon, folks.

[MainFrame65]

As earthquake-prone as Japan is, they have a VERY sensitive and sophisticated seismic network. They can probably detect when Kim Jong-Il passes gas. Kimchi can do that to you....