2013 North Korean nuclear test

On 12 February 2013, North Korean state media announced it had conducted an underground nuclear test, its third in seven years. A tremor that exhibited a nuclear bomb signature with an initial magnitude 4.9 (later revised to 5.1) was detected by The China Earthquake Networks Center, Comprehensive Nuclear-Test-Ban Treaty Organization Preparatory Commission and the United States Geological Survey. In response, Japan summoned an emergency United Nations meeting for 12 February and South Korea raised its military alert status. It is not known if the explosion was nuclear, or a conventional explosion designed to mimic a nuclear blast; as of two days after the blast, Chinese, Japanese, and South Korean investigators had failed to detect any radiation.

Test


On 12 February 2013, a spokesman for North Korea's army command said it had successfully conducted a third underground nuclear weapons test, according to the Yonhap. North Korea also said the test had used a miniaturized nuclear device with greater explosive power.

Before North Korea announced they had conducted the test, seismic activity had already been detected in North Korea by the USGS, near the site of previous nuclear tests at Mantapsan in Kilju County. A large tremor, first estimated at magnitude of 4.9, was detected in North Korea and governments in the region were trying to determine whether it was a third nuclear test. The USGS upgraded the magnitude of the possibly nuclear tremor from 4.9 to 5.1, located 24 km east-northeast of Sungjibaegam, North Korea. The tremor occurred at 11:57am KST (2:57am UTC) and the USGS said the hypocenter of the event was only one kilometer deep. Later, the Geophysical Service of the Russian Academy of Sciences did not register any seismic events and underground tremors at 16:00 local time on 12 February 2013, in the Russian Far East. The China Earthquake Networks Center (Abbreviation: CENC; ) also reported this event, putting the magnitude at Ms 4.9. The tremor caused by the test could be felt by residents of the neighboring city of Hunchun and Antu, in Yanbian, Jilin Province, China. A citizen of Hyesan, Ryanggang Province of North Korea, 80 km west from the nuclear test site, reported that many 5- and 7-floor buildings shook very severely, and this caused cracking.

Yield estimates
South Korea's defense ministry said the event reading indicated a blast of 6–7 kilotons,  later revised to 6–9 kilotons using the Comprehensive Nuclear Test Ban Treaty Organization’s calculation method. The Korea Institute of Geosciences and Mineral Resources estimated the yield as 7.7–7.8 kilotons.

Some experts estimate the yield to be up to 15 kilotons, since the test site's geology is not well understood. The Russian Defence Ministry said the power of North Korea's nuclear test blast surpassed 7 kilotons. NORSAR compared the seismic data from all three North Korean nuclear tests and estimated the yield of the 2013 test as approximately 10 kilotons. However, the Federal Institute for Geosciences and Natural Resources, a state-run geology research institute in Germany, estimated the yield at 40 kilotons.

On 2013 June 19, the University of Science and Technology of China had released a report that claimed that they had found the precise location of the test at Latitude 41 degrees 17 minutes 26.88 seconds, longitude 129 degrees 4 minutes 34.68 seconds with an error margin of mere 94 meters and the yield at around 12.2 kt, with a margin of error of 3.8 kt.

In comparison, the atomic (fission) bombs dropped by the Enola Gay on Hiroshima (Little Boy, a "gun-type" atomic bomb) and on Nagasaki by Bockscar (Fat Man, an "implosion-type" atomic bomb) had blast yield equivalence of 16 and 21 kilotons respectively.

Further tests
On February 4, 2013, a South Korean military official had stated that there was a "chance that the southern tunnel is a decoy, but we are not ruling out that the regime will conduct nuclear tests simultaneously at both tunnels." On February 15, 2013, North Korea had told China that they were preparing for one or two more nuclear tests this year. On April 8, 2013, South Korea had observed activity at Punggye-ri, suggesting that a fourth underground test was being prepared. It was later believed that the tunneling activity that started in April was for a long term project, and that a nuclear test wouldn't occur soon. According to a U.S. expert, North Korea has everything in place for a fourth explosion but is hesitating due to the fear that it would anger China.

Reaction
In response, Japan's Prime Minister, Shinzo Abe, called an urgent security meeting of the United Nations Security Council. The emergency session was to be held 9 AM EST on February 12, 2013. Tibor Toth, executive secretary of the Comprehensive Nuclear-Test-Ban Treaty Organization Preparatory Commission (CTBTO), confirmed the event's location was "roughly congruent with" nuclear tests carried out by North Korea in 2006 and 2009. Japan's Kyodo News service reported the Japanese defense ministry had scrambled aircraft to hunt for radiation effects. Japan's government held a national security council meeting in Tokyo according to NHK. The South Korean military also raised its readiness level. In general, international reactions to the 2013 North Korean nuclear test have been almost uniformly negative.