North Korean Yield RevisedJeff over at armscontrolwonk.com, has posted a nice set of estimates of the yield for the NORK test. They all cluster in an Mb range of 4.5-5.0 -- about 2-6 kilotons.
In depth analysis: North KoreaThe Project for the CTBT has a calculation from Martin Kalinowski:
The U.S. Geological Survey readings indicate a seismic body wave of magnitude of 4.7, which is larger as compared to the value of 4.1 ± 0.1 in 2006. According a preliminary assessment by Martin Kalinowski of the University of Hamburg, this corresponds to an explosive yield of about 3 to 8 kilotons TNT equivalent with a most likely yield of 4 kt. In 2006. The yield of the 2006 test explosion was approximately 0.5 to 0.8 kt TNT equivalent.
Here is Kalinowski's fact sheet.
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North Korea conducts a second nuclear testRussia's Defense Ministry confirmed an atomic explosion at 9:54 a.m. (0054 GMT) in northeastern North Korea, estimating the blast's yield at 10 to 20 kilotons - comparable to the bombs that destroyed Hiroshima and Nagasaki.
Monday's atomic test was conducted about 50 miles (80 kilometers) northwest of the northern city of Kilju, Russian Defense Ministry spokesman Alexander Drobyshevsky said, speaking on state-run Rossiya television. Here is a Google Earth kmz of the test site.
Kilju, in the northeastern province of North Hamgyong, is where North Korea conducted its first nuclear test in October 2006.
Pyongyang is believed to have enough weaponized plutonium for at least a half-dozen atomic bombs. However, experts say scientists have not yet mastered the miniaturization needed to mount a nuclear device onto a long-range missile.
Hours later, the regime test-fired three short-range, ground-to-air missiles, the Yonhap news agency reported, citing unnamed sources. U.N. Security Council resolutions bar North Korea from engaging in any ballistic missile-related activity. [via MSNBC.com and Arms Control Wonk]
Herbert York PassesDr. Herbert York, the first director of Lawrence Livermore Laboratory, died on May 19, 2009 of leukemia. In addition, Dr. York served as Chancellor of the University of California, San Diego, from 1961 to 1964, and again from 1970 to 1972.
Additionally, York has written some 75 articles and several books, including Race to Oblivion: A Participant's View of the Arms Race. His awards include the E.O. Lawrence Prize (1964), a Guggenheim Fellowship (1972-73), and the American Physical Society's Leo Szilard Award for Physics in the Public Interest (1994). In 2000, President Clinton named him a recipient of the Enrico Fermi Award for his efforts and contributions in nuclear deterrence and arms-control agreements.
I had the pleasure of hearing speak a few years ago at UCSD on Physicists, the Bomb and the Development of U.S. Science Policy. That event can be viewed here.