North Korea confirms third nuclear test causing a 4.9-5.1 magnitude tremor

[Emily]

http://www.washingtonpost.com/world/asia_pacific/in-north-korea-seismic-activity-detected-near-nuclear-test-site/2013/02/11/1fcf0e4a-74c9-11e2-95e4-6148e45d7adb_story.html

By Chico Harlan, Updated: Monday, February 11, 9:50 PM

SEOUL ? North Korea on Tuesday conducted an underground explosion of what it called a ?miniaturized? nuclear weapon, testing a technology that could theoretically be paired with a long-range missile to threaten the United States.

Pyongyang confirmed the test nearly three hours after unusual seismic activity was detected near the secretive police state?s mountainous test site. The test follows weeks of threats from the North to build up its nuclear capacity and carry out an ?all-out action of high intensity.?.
[snip]
The U.S. Geological Survey detected a 4.9-magnitude tremor at 11:58 a.m. local time in North Korea. ...

Upped to a 5.1. How ?miniaturized? is that?
http://earthquake.usgs.gov/earthquakes/eventpage/usc000f5t0#summary
M5.1 - 23km ENE of Sungjibaegam, North Korea 2013-02-12 02:57:51 UTC