Study: Radar imaging shows how the mountain collapsed after North Korea’s most recent nuclear test
As North Korea’s president pledges to “denuclearize” the Korean peninsula, an international team of scientists is publishing the most detailed view yet of the site of the country’s latest and largest underground nuclear test on Sept. 3, 2017.
The new picture of how the explosion altered the mountain above the detonation highlights the importance of using satellite radar imaging, called SAR (synthetic aperture radar), in addition to seismic recordings to more precisely monitor the location and yield of nuclear tests in North Korea and around the world.
The researchers—Teng Wang, Qibin Shi, Shengji Wei and Sylvain Barbot from Nanyang Technological University in Singapore, Douglas Dreger and Roland Bürgmann from the University of California, Berkeley, Mehdi Nikkhoo from the German Research Centre for Geosciences in Potsdam, Mahdi Motagh from the Leibniz Universität Hannover, and Qi-Fu Chen from the Chinese Academy of Sciences in Beijing—will report their results online this week in advance of publication in the journal Science.
Three-dimensional (3D) displacement associated with the 3 September 2017 North Korean Nuclear Test (NKNT 6).
(A) 3D displacements derived from radar imagery with arrows indicating horizontal, color indicating vertical motions spanning the explosion and ~1 week of additional deformation. The uncertainties are shown in fig. S4 and provided in data S1 with the displacements. Black outline derived from ALOS-2 coherence loss indicates the substantial surface disturbance and large displacement gradients caused by the explosion over an area of ~9 km2 (figs. S1 and S2). Thin gray lines are topographic contours at 100-m intervals. Red square in the upper right inset shows the location of Mt. Mantap. Red stars indicate the locations of NKNT 1-5 (1, 6, 9, 15, 37), among which NKNT 2-5 were all located within the NKNT-6 low-coherence region, NKNT 1 on 9 October 2006 was in a different location (5). Beach balls show locations and focal mechanisms of the Mw 5.24 and Mw 4.47 events on 3 September 2017. (B and C) 2D (horizontal along the profile and vertical) displacements along two profiles across the top of Mt Mantap from north to south, and from west to east respectively. The elevations along the vertical axis in (B) and (C) are on scale.
That explosion took place under Mt. Mantap at the Punggye-ri nuclear test site in the country’s north, rocking the area like a 5.2-magnitude earthquake. Based on seismic recordings from global and regional networks, and before-and-after radar measurements of the ground surface from Germany’s TerraSAR-X and Japan’s ALOS-2 radar imaging satellites, the team showed that the underground nuclear blast pushed the surface of Mt. Mantap outward by as much as 11 feet (3.5 meters) and left the mountain about 20 inches (0.5 meters) shorter.
By modelling the event on a computer, they were able to pinpoint the location of the explosion, directly under the mile-high summit, and its depth, between a quarter and a third of a mile (400-600 meters) below the peak.
They also located more precisely another seismic event, or aftershock, that occurred 8.5 minutes after the nuclear explosion, putting it some 2,300 feet (700 meters) south of the bomb blast. This is about halfway between the site of the nuclear detonation and an access tunnel entrance and may have been caused by the collapse of part of the tunnel or of a cavity remaining from a previous nuclear explosion.
“This is the first time the complete three-dimensional surface displacements associated with an underground nuclear test were imaged and presented to the public,” said lead author Teng Wang of the Earth Observatory of Singapore at Nanyang Technological University.
Read more at: https://phys.org/news/2018-05-radar-reveals-mountain-collapse-north.html
From Science Magazine, the paper: http://science.sciencemag.org/content/early/2018/05/09/science.aar7230.full
The rise, collapse, and compaction of Mt. Mantap from the 3 September 2017 North Korean nuclear test
Abstract
Surveillance of clandestine nuclear tests relies on a global seismic network, but the potential of spaceborne monitoring has been underexploited. Here, we determined the complete surface displacement field of up to 3.5 m of divergent horizontal motion with 0.5 m of subsidence associated with North Korea’s largest underground nuclear test using satellite radar imagery. Combining insight from geodetic and seismological remote sensing, we found that the aftermath of the initial explosive deformation involved subsidence associated with sub-surface collapse and aseismic compaction of the damaged rocks of the test site. The explosive yield from the nuclear detonation with seismic modeling for 450m depth was between 120-304 kt of TNT equivalent. Our results demonstrate the capability of spaceborne remote sensing to help characterize large underground nuclear tests.
Excerpts:
Model geometry and fit to the observed surface displacements.
(A) Perspective view of the model with topography and variance reductions as a function of centroid position (both cross-sections are centered on the best fit location). We represent the first event, combining the explosion and immediate collapse, using a sphere of 300 m radius with a centroid located at a depth about 450 m below Mt Mantap. We model the aseismic subsidence detected with geodetic data about a week after the seismic events 1 and 2 with an ellipsoid of dimension 800 × 800 × 470 m semi-axes, centered at 100 m deeper than the explosive source. The isotropic components of the moment tensors are represented as beach balls. (B) The observed and simulated surface displacements. (C) The west-east and south-north profiles of the surface displacements from the SAR observations and the best-fitting models. The dashed profiles represent the contributions of the explosion/collapse (Event 1) and the subsequent aseismic compaction on the surface displacement. We ignore the deformation caused by Event 2.
Analysis of seismic waves.
(A) Station map of broadband seismometers with four stations in (B) and (D) highlighted in red. The black and red stars are the epicenter location of the first and second event, respectively. (B) Moment tensor solutions for the first explosive (left) and the second implosive (right) event, with vertical component of two representative stations shown at the bottom. Both data and synthetics are filtered between 0.02 and 0.045 Hz. Station names are shown at the beginning of waveform pairs and distance (in km) and azimuth (in degree) are indicated below. (C) Grid search result (under L1 norm) for relocating the second event relative to the first event (black star). Marginal distribution for the epicentral position are plotted along the northing and easting axes. (D) Vertical component waveform comparison between the first (black) and the second (red) event at two representative stations, with the second event waveforms multiplied by -60. (E) Explosive yield with historical nuclear tests. The black dots and error bars show yields estimated based on the mean and standard deviation of tabulated moment within 95% of the best fitting solutions with depths of 300, 450 and 600 m respectively.
Combining the available space-borne geodetic and seismic records provided new insights into the mechanics of deformation surrounding North Korea’s sixth underground nuclear test, revealing the explosion, collapse, and subsequent compaction sequence (Fig. 4). The modeling of the geodetic observations reduces the epicentral and depth uncertainties that otherwise hinder the analysis of seismic waveforms. The derived horizontal location of the first event is important to relatively relocate the second event, which likely indicates the collapse of the tunnel system of the test site. The inclusion of geodetic data also helps resolving the aseismic deformation processes that may follow nuclear tests. Finally, our findings demonstrate the capability of monitoring shallow underground nuclear tests using remote-sensing observations and seismic sensors.
Summary deformation scenario for the 3 September 2017 North Korea’s Nuclear test.
The unfolding of events includes the succession of (A) explosive, (B) collapse, and (D) compaction processes, with different associated surface displacements. The implosive source (C) may be shallow and only contribute localized surface displacements. The radar imagery reveals the deformation (arrows in (D)] resulting from the three processes.
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Did Kim lose his trump card?
What if the collapse resulted in a release of radioactivity or nearly did so. Would that prompt the Chinese to step in and say “no mas”?
@ur momisugly Oatley:
In answer to your question, YES. This has been my take for some time….. since it was first rumored that the site had collapsed. The Chinese are concerned about radioactive fallout and are putting heavy pressure on ‘Lil Kim.
What is surprising to me is that it took this long for the thread to come to this question.
“What is surprising to me is that it took this long for the thread to come to this question.”
It was addressed upthread by yours truly. You missed it.
Here is a thought. As noted above there was a rescue attempt to try and save the several hundred workers trapped in the collapsed tunnel. The question is would they have even mounted a rescue mission, if those trapped inside were merely replaceable workers? This could be a strong indicator that there were some important people inside when the tunnel collapsed.
“This could be a strong indicator that there were some important people inside when the tunnel collapsed.”
It would be too bad if some Iranian nuclear scientists got caught in the collapse of the North Korean nuclear test facility..
Enough brainpower to make progress in nuclear field as well as in the rocket field, at a pace never seen in history, not enough brainpower to have some remote sensors and avoid getting crunched?
Forgive my ignorance…why would there even be people in the tunnel, let alone the entire mountain. Aren’t these things remotely monitored?
North Korea and Iran is the topic in this special addition of Hannity, starting at 36 min. 46 sec.
One of the 3 guests on the topic, Lt. Col. (Res) Michael Waltz said, “”Both N. Korea and Iran are linked in so many ways. There have been N. Korea chemical engineers in Syria. Don’t forget that the Israeli’s bombed a ‘N. Korean built’ nuclear reactor in Syria years ago, also backed by Iran. These are linkages, strategic linkages, that Amb. Bolton, Pres. Trump, Sec’y Mattis understand and know how to go after and that’s why you are seeing real results from the Trump administration.””
Gordon Chang says, “”As we know these two programs are linked. We have Iranian technicians in N. Korea. The Iranian technicians have seen the N. Korean nuclear detonations, they’ve been there. So, these two regimes are joined at the hip. Iran is supposed to pay N. Korea something like, 2 and a half to 3 billion dollars a year for their various forms of cooperation. And that’s a real indication that the two nations, the two regimes, are so close together.””
https://youtu.be/EjNRLKLbcWg?t=36m46s
President Trump is announcing that if Kim Jung un cooperates and gets rid of his nukes, the U.S. will help North Korea to become an economy equal to South Korea.
Kim is going to need a lot of electricity. (place nightime satellite photo of Korea with the South lit up like a christmas tree, and the North in a blackout, here)
That’s “Chairman Kim”, btw. Or at least that is what Secretary of State Pompeo called him the other day.
It’s funny, the radical Left were wringing their hands and telling Trump to stop it, when Trump was calling Kim “Little rocketman”.
Now that the Trump administration has moderated their tone towards Kim because of the upcoming summit, the radical Left is complaining that Trump is not being hard enough on Kim, rhetorically. Trump is not being harsh enough on Kim the Libs now claim.
It doesn’t matter what Trump does, the radical Left is not going to like it. TDS. Maybe I shouldn’t call it that since the radical Left does have a legitimate grip with Trump since he is dismantling their socialist agenda piece after piece. But they still have TDS really bad. 🙂