Here’s the USGS report, coming in at 4.9, and here’s the first report saying it looks like a nuke test. In case you’re keeping track, North Korea’s 2009 test measured 4.7 on the Richter scale after a yield estimated between 2 and 8 kilotons. Its 2006 test registered 4.2, at a yield of just under a kiloton. Remember — this is a logarithmic scale, which means that a 5 is ten times larger than a 4.
Anyway, a nuclear test site isn’t the only thing newsworthy in that vicinity. If you wonder if the North Koreans are evil enough to actually use one of their new toys, well, have a look around the neighborhood.