Whatever you decide to buy, don't just buy certificates. Make certain it is hard metal and in your own hands.
My bad. Ignore first link.
I doubt it, but I'm not a geologist.
Heard a tremendous boom about an hour and a-half ago. Sounded just like a thunder clap, and it was raining at the time. But when i looked at weather radar, there were no t-storms to account for it.