Here’s possible confirmation of the nuclear test in North Korea, the USGS has a report of a magnitude 4.2 quake near Chongjin, North Korea. Capture of the map is below.

Update 2014-09-30: Please note that the above links no longer work, thanks to Sharon Thornton (Research Coordinator at The International Union of Geodesy and Geophysics) for pointing that out. Instead here is an alternative URL with information about the quake and also a PDF report on it from the Center for Nonproliferation Studies and the Monterey Institute of International Studies.