Special Event: North Korea nuclear explosion

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On Feb 12, 2013, a magnitude 5.1 event was recorded in North Korea. Preliminary results suggests that a nuclear test took place.

Event parameters (from USGS)

These are preliminary results and are subject to change without notice. Please check the USGS page for the latest official information.

Magnitude 5.1
UTC Time Tuesday, February 12, 2013 at 02:57:51 UTC
Local Time Tuesday, February 12, 2013 at 11:57:51 (UTC+9) at epicenter
Location 41.307°N, 129.076°E
Depth 0.0km (0.0 miles)
Region ENE of Sungjibaegam, North Korea
Distances 24km (15mi) ENE of Sungjibaegam, North Korea
24km (15mi) ENE of Sungjibaegam, North Korea
35km (22mi) WNW of Hau-ri, North Korea
43km (27mi) NNW of Kilju, North Korea
379km (235mi) NE of Pyongyang, North Korea
Details USGS

IRIS Education and Public Outreach and the University of Portland have established routine procedures to develop a set of “Teachable Moments” which provide a short summary of the latest major earthquake within a few hours to one day after an event. Prepared by seismologists and educators, “Teachable Moments” include powerpoint slides, .pdf presentations and animations.

Event Plots of data (IRIS DMC)

Magnitude 5.1 North Korea Teachable Moment (IRIS)

Links

USGS event summary page (USGS)

USGS poster for this event (USGS)

http://www.norsar.no/norsar/about-us/News/NuclearExplosionDPRK12Feb2013 (NORSAR)

http://www.geophysique.be/2013/02/12/north-korean-nuclear-tests-with-obspy/ Thomas Lecocq (Royal Observatory of Belgium)

Uniformly scaled seismograms from MDJ for 2006, 2009 & 2013 event on one plot Zhigang Peng (Georgia Tech)
The accompanying sonogram Zhigang Peng (Georgia Tech)

http://anf.ucsd.edu/spevents/2013/043/a/ (Array Network Facility, UC San Diego)

Images and movies

North Korea M5.1 vs Nevada M5.1 seismograms

Figure 1: Seismograms from two equidistant stations from the (left) 2013/02/12 North Korean M5.1 event and the (right) 2013/02/13 Nevada M5.1 earthquake. See audio representation of these two events in the SeisSound examples below. (IRIS DMC)


Seismograms of North Koreas test's

Figure 2: Seismograms showing vertical ground velocity from North Korea’s October 2006 test (green), May 2009 test (red), and February 2013 test (blue) as recorded at GSN/China Digital Seismic Network station MDJ. A 0.5 Hz high-pass filter has been applied. (IRIS DMC)


Overlapping traces from 2009 & 2013

Figure 3: Strikingly similar vertical displacement records from 2009 and 2013 North Korean nuclear tests, with amplitudes normalized. (IRIS DMC)


Moment tensor using just station MDJ

Figure 5: Moment tensor using just station MDJ (contributed by Katherine Whidden & Keith Koper at U Utah).


Nice PKP record from GT.LPAZ at different frequencies. Dist=150.9*

Figure 6: Nice PKP record from GT.LPAZ at different frequencies. Dist=150.9* Click here for Travel Times via WebServices


Equally filtered seismograms from the North Korean explosion and the Feb 15 meteorite explosion in Siberia.  Top: raw   Middle:  low pass below 10 sec  Bottom:  high pass above 1 s.

Figure 7: Quick comparison of the Feb 15th meteor explosion near Chelyabinsk, Russia and the Feb. 12 North Korean nuclear explosion recorded a few hundred kilometers away. The top panel shows raw data, middle low-pass filtered below 10s, and bottom high-pass above 1 s. Because of a lack of coupling to the ground for the meteor explosion, only long distance signals are recorded at long-range distances. (contributed by Zhigang Peng, Georgia Tech)


2013 N. Korean test yield estimate, using 2009 test as a template

Figure 8: Because the earlier and 2013 nuclear tests in North Korea we conducted in almost the same place, and produced very similar seismic sources (except for size), it is straightforward to get a rapid estimate of the yield of the 2013 test using the careful estimates made for earlier ones. A comparison of squared velocity seismograms (which are proportional to seismic energy) at station MDJ in China (Mudanjiang, Heilongjiang Province) approximately 380 km from the test site, produces a most likely yield of 19.8 kilotons, based on the 2009 estimates by Kalinowski et al. http://www.armscontrolwonk.com/file_download/177/Kalinowski.pdf , with minimum and maxim yields of 14.8 and 39.5 kilotons. This analysis shows that the 2013 test was approximately 4.9 times larger in energy than the 2009 test (and about 62 times larger than the 2006 test). The USGS NEIC magnitude and a commonly used regression from Nuttli, 1986 developed for the Nevada Test Site are shown for comparison (note that the Nuttli magnitude scale differs somewhat from the USGS scale for body wave magnitude). (Rick Aster, New Mexico Tech)


Sonification of a seismogram from the North Korean explosion

Video 1: SeisSound, the Audio/Video Seismic Waveform Visualization of the M5.1 North Korea's test (depth ~1 km) of February 12, 2013 seismogram recorded at station MDJ (at about 370 km from the test site). A 0.5 Hz high-pass filter is applied and a speed up factor of 500 is used to transform the seismogram frequencies to audible range. IRIS DMS Products.

Comparison with a natural earthquake

Video 2: SeisSound, the Audio/Video Seismic Waveform Visualization of the M5.2 California-Nevada Border Region earthquake (depth 12 km) of February 13, 2013 seismogram recorded at station SAO (at about 330 km from the event, approximately the same distance as station MDJ from the North Korea's test). A 0.5 Hz high-pass filter is applied and a speed up factor of 500 is used to transform the seismogram frequencies to audible range. IRIS DMS Products.

All 3 nuclear tests at station MDJ using the same scaling (Zhigang Peng, Georgia Tech)

Video 3: Seismograms & Sonograms from the 3 North Korean tests at station MDJ. (Zhigang Peng, Georgia Tech)

Relocation exercise and example results

Relocation exercise example results

Figure 4: Example results from the relocation exercise using data available from IRIS. Left panel shows locations in this basic exercise of the 2006 (black cirlce) and 2013 (blue circle) relative to the 2009 event which is used as the reference. The middle and right panel show best fitting sinusoids of travel time residuals to the observed residuals from cross-correlation (codes provided in zip file below). The data are from nearby stations and a constant Pn velocity and is assumed as well as initial co-locations of events. The differences (as a function of azimuth) between predicted and observed delays in arrivals of Pn (at e.g. station MDJ at azimuth=6) are plotted on the y-axes.

Zip file with SAC files and fortran and matlab codes to do this exercise yourself (Alex Hutko IRIS DMC)

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north special-event korea 5.1 retm test nuclear gsn IRIS NK explosion

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