I'm sorry, I've only skimmed through the posts so forgive me if this has been said already:
I read a website once that said when Apollo 13 (?) shot the lunar module into the moon, NASA said it "rang like a bell for an hour". This
supposedly led to the idea that the moon may very well be hollow.
Here's the seismic graph reading after the lunar module crashed into the moon:
Could this be another test of that?
Also, Japan JUST did the same thing. Apparently, they just did the same thing in February. What's with all the bomb dropping up there?
Japan's Moon Probe Makes Crash Landing
I don't know if I buy into all the hollow moon stuff, but I just thought it was worth mentioning for a different perspective.