From the DailyMail.com:
North Korea has launched its sixth nuclear test, sparking a powerful 6.3 magnitude earthquake.
Japanese officials have confirmed the quake, which was detected in the northeast of the country where North Korea’s nuclear test site Punggye-ri is located, was caused by a nuclear explosion.
Japan’s Ministry of Defence has dispatched three military jets to test for radiation.
A US researcher told the BBC that if the earthquake was caused by a nuclear blast, it would be the largest atomic test conducted by North Korea.
Dave Schmerler, of the James Martin Center for Nonproliferation Studies: “This would be the largest nuclear test that North Korea has ever conducted. We should definitely be alarmed.’