[dead]

And the US snooper aircraft would immediately tell CNN and we would all know about it?

There would be plenty of civilian detectors that would know about the radiation spike and would share that information with anybody who cared to broadcast it.

That's one of the reasons the Soviets couldn't cover up Chernobyl.

The big difference here though, is Chernobyl actually was a nuclear event and this was a regular old earthquake.

[faq]

Oh no! The Chinese have stolen design plans for our natural disaster machine.

[TBall]

I agree that people would talk about sensors going off, but that is not to say that it would make mainstream news.

[count-your-change]

A nuke explosion also has its own unique signal through the earth which is how an underground test shows up on sensors around the world. The signal of an earthquake is different and the difference is easily detected. Some what analogous to running different signals over a phone line.