North Korea Thread: DPRK Launching Missiles With New ICBM
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How science knows when nations are testing nuclear bombs — even when they are lying
Earthquakes vs bombs
Every time an earthquake happens, thousands of devices all around the world record it. These are the seismographs, and they measure movements associated with earthquakes. This global network has proven instrumental for a number of reasons.
For starters, we can know the location of all earthquakes (to some degree of certainty). We’ve long deduced the speed of seismic waves, and by calculating the arrival time of these waves at different places across the Earth’s surface, we can know where an earthquake happened and triangulate the epicenter. This also helped us greatly expand our understanding of the planet’s subsurface, and earthquakes allow us to “see” way deeper than we could ever hope otherwise.
We can also tell a lot about the earthquake intensity — its energy. The Richter magnitude (the most commonly used scale) is basically determined from the logarithm of the amplitude of waves recorded by seismographs. So an earthquake with a magnitude of 7 is ten times stronger than that with a magnitude of 6. But we can go even deeper into the mechanism of the earthquake: we can study its source, through the waves we see.
All earthquakes have three types of waves: P waves (primary), S waves (secondary), and surface wave (Love and Rayleigh waves). This is where it really gets interesting.
The different types of seismic waves.
Although surface waves are typically the most destructive, P waves are the fastest. These P waves are essentially alternative extensions and compressions of matter along a trajectory — think of someone playing the accordion. Now, imagine an earthquake happening. Some part of the ground snaps. When it triggers, it produces these waves, and if you plot P waves over a stereographic projection, you end up with a so-called beachball diagram. These diagrams show that for the first movement, some directions are extensions, while the perpendicular directions are contractions. It’s not the easiest thing to wrap your head around, but let’s just say that for every earthquake, P waves start as extensions over half of all possible directions, and contractions in the other half.
Types of ‘beachball’ plots associated with fault end-members. A diagram for an explosion would be all black. Image via Wikipedia.
Whenever an underground explosion happens, it only produces contractions. So for an underground explosion, you wouldn’t end up with a beachball diagram that’s half white and half black — you’d end up with one that’s all black. In other words, the pattern of energy in a bomb-related earthquake is completely different than that of a natural earthquake.
“As the bomb is detonating, it’s compressing the rock immediately adjacent to it, and that propagates out to the recording stations” as P waves, said Douglas Dreger, a seismologist at the University of California, Berkeley.
The relative amplitude of waves can also be an indicator of an explosion and not a natural earthquake. The bottom line is, you can’t really fake the seismic signature of an underground explosion — people will be able to tell whether or not you tested a bomb, and approximately how strong it is.
[Also read our previous article on this topic: Did North Korea actually test a bomb? Science has the answer]
Why underground?
While we’re discussing detecting underground explosions, it makes sense to ask the question — why underground? Why not just test it in the air, or underwater? Well, if you want to hide something, underground is just your best bet. People will still know you did something, but you have a decent chance to at least hide some information.
Air does very little to muffle the sound of an explosion. Furthermore, explosions also generate infrasonic (long wavelength, low frequency) waves that are very easy to pick up on detectors all around the world. Radiation might also be detected. So if you want to carry an experiment, air does basically nothing to hide it.
Water is a bit better. The energy of the waves dissipates more than in air, but since there are no natural sources that can produce such earthquakes underwater, you’d again be creating an easily detectable smoking gun.
By going underground, you’re at least putting a mask on your smoking gun. Vigilant observers will still be able to see what you’re doing, but at least you’ll be making it hard for them, and if you’re lucky, you might create some uncertainty around the energy of the bomb.
Routine measurements
Basically, only North Korea is testing nuclear weapons at this point. Image via Wikipedia.
This is not really groundbreaking science — it’s been known for decades. It’s this technology that allowed the implementation of the Treaty on the Non-Proliferation of Nuclear Weapons, commonly known as the Non-Proliferation Treaty. According to the treaty, no nation is allowed to conduct nuclear tests, but there’s not much point in having such a deal if you can’t verify it, is there?
So most nations on Earth have at least some form of seismological monitoring which not only studies earthquakes but also detects such explosions. We can’t really know what kind of a bomb it is (was it really an H bomb?), but we can infer several things about it, with decent certainty.
The biggest question is, was it fusion or fission? Both bomb types release large quantities of energy from relatively small amounts of matter. However, the fundamental principle is different. Fission bombs use heavy elements such as uranium and plutonium and break them down into unstable isotopes when bombarded with neutrons. Meanwhile, fusion bombs take the opposite approach: they use light elements such as hydrogen and combine them into heavier elements such as helium, releasing even more energy in the process. The required energy is so great, that the only way we’ve figured out to make such a bomb is by surrounding it with a fission bomb to power it up.
A-bomb vs H-bomb comparison. Image via Wikipedia.
So you can get an idea about the scale we’re talking, the first test of a fission (“atomic”) bomb released an amount of energy approximately equal to 20,000 tons of TN. The first thermonuclear (“hydrogen”) bomb test released energy approximately equal to 10 million tons of TNT.
North Korea’s tests
The figure below shows the estimated locations within the Pungggye-ri test site of the five previous tests (red dots). The tests are conducted in the tunnel system inside the mountain. The area of the likely location of the most recent test is indicated in the figure. Some additional work is required in order to estimate a precise location. Image credits: Norsar seismic array.
This leads us to North Korea’s tests. They claim to have tested a hydrogen bomb, but judging by the energy observed in the North Korean tests, there’s almost no way that’s true. If it were indeed an H bomb, it would be the most efficient fussion we’ve ever seen, something many researchers don’t even believe is possible. So right now, all the evidence is pointing towards a fission bomb, what’s often called an atomic bomb. It’s possible that they did assemble an H bomb, but for some reason, it failed, or that they’re just bluffing. Even an atomic bomb would likely be enough to completely wipe an average city, so this shouldn’t be treated lightly. In fact, few things are as frightening as a nuclear war.
So here’s what we know so far:
Earthquakes vs bombs
Every time an earthquake happens, thousands of devices all around the world record it. These are the seismographs, and they measure movements associated with earthquakes. This global network has proven instrumental for a number of reasons.
For starters, we can know the location of all earthquakes (to some degree of certainty). We’ve long deduced the speed of seismic waves, and by calculating the arrival time of these waves at different places across the Earth’s surface, we can know where an earthquake happened and triangulate the epicenter. This also helped us greatly expand our understanding of the planet’s subsurface, and earthquakes allow us to “see” way deeper than we could ever hope otherwise.
We can also tell a lot about the earthquake intensity — its energy. The Richter magnitude (the most commonly used scale) is basically determined from the logarithm of the amplitude of waves recorded by seismographs. So an earthquake with a magnitude of 7 is ten times stronger than that with a magnitude of 6. But we can go even deeper into the mechanism of the earthquake: we can study its source, through the waves we see.
All earthquakes have three types of waves: P waves (primary), S waves (secondary), and surface wave (Love and Rayleigh waves). This is where it really gets interesting.
The different types of seismic waves.
Although surface waves are typically the most destructive, P waves are the fastest. These P waves are essentially alternative extensions and compressions of matter along a trajectory — think of someone playing the accordion. Now, imagine an earthquake happening. Some part of the ground snaps. When it triggers, it produces these waves, and if you plot P waves over a stereographic projection, you end up with a so-called beachball diagram. These diagrams show that for the first movement, some directions are extensions, while the perpendicular directions are contractions. It’s not the easiest thing to wrap your head around, but let’s just say that for every earthquake, P waves start as extensions over half of all possible directions, and contractions in the other half.
Types of ‘beachball’ plots associated with fault end-members. A diagram for an explosion would be all black. Image via Wikipedia.
Whenever an underground explosion happens, it only produces contractions. So for an underground explosion, you wouldn’t end up with a beachball diagram that’s half white and half black — you’d end up with one that’s all black. In other words, the pattern of energy in a bomb-related earthquake is completely different than that of a natural earthquake.
“As the bomb is detonating, it’s compressing the rock immediately adjacent to it, and that propagates out to the recording stations” as P waves, said Douglas Dreger, a seismologist at the University of California, Berkeley.
The relative amplitude of waves can also be an indicator of an explosion and not a natural earthquake. The bottom line is, you can’t really fake the seismic signature of an underground explosion — people will be able to tell whether or not you tested a bomb, and approximately how strong it is.
[Also read our previous article on this topic: Did North Korea actually test a bomb? Science has the answer]
Why underground?
While we’re discussing detecting underground explosions, it makes sense to ask the question — why underground? Why not just test it in the air, or underwater? Well, if you want to hide something, underground is just your best bet. People will still know you did something, but you have a decent chance to at least hide some information.
Air does very little to muffle the sound of an explosion. Furthermore, explosions also generate infrasonic (long wavelength, low frequency) waves that are very easy to pick up on detectors all around the world. Radiation might also be detected. So if you want to carry an experiment, air does basically nothing to hide it.
Water is a bit better. The energy of the waves dissipates more than in air, but since there are no natural sources that can produce such earthquakes underwater, you’d again be creating an easily detectable smoking gun.
By going underground, you’re at least putting a mask on your smoking gun. Vigilant observers will still be able to see what you’re doing, but at least you’ll be making it hard for them, and if you’re lucky, you might create some uncertainty around the energy of the bomb.
Routine measurements
Basically, only North Korea is testing nuclear weapons at this point. Image via Wikipedia.
This is not really groundbreaking science — it’s been known for decades. It’s this technology that allowed the implementation of the Treaty on the Non-Proliferation of Nuclear Weapons, commonly known as the Non-Proliferation Treaty. According to the treaty, no nation is allowed to conduct nuclear tests, but there’s not much point in having such a deal if you can’t verify it, is there?
So most nations on Earth have at least some form of seismological monitoring which not only studies earthquakes but also detects such explosions. We can’t really know what kind of a bomb it is (was it really an H bomb?), but we can infer several things about it, with decent certainty.
The biggest question is, was it fusion or fission? Both bomb types release large quantities of energy from relatively small amounts of matter. However, the fundamental principle is different. Fission bombs use heavy elements such as uranium and plutonium and break them down into unstable isotopes when bombarded with neutrons. Meanwhile, fusion bombs take the opposite approach: they use light elements such as hydrogen and combine them into heavier elements such as helium, releasing even more energy in the process. The required energy is so great, that the only way we’ve figured out to make such a bomb is by surrounding it with a fission bomb to power it up.
A-bomb vs H-bomb comparison. Image via Wikipedia.
So you can get an idea about the scale we’re talking, the first test of a fission (“atomic”) bomb released an amount of energy approximately equal to 20,000 tons of TN. The first thermonuclear (“hydrogen”) bomb test released energy approximately equal to 10 million tons of TNT.
North Korea’s tests
The figure below shows the estimated locations within the Pungggye-ri test site of the five previous tests (red dots). The tests are conducted in the tunnel system inside the mountain. The area of the likely location of the most recent test is indicated in the figure. Some additional work is required in order to estimate a precise location. Image credits: Norsar seismic array.
This leads us to North Korea’s tests. They claim to have tested a hydrogen bomb, but judging by the energy observed in the North Korean tests, there’s almost no way that’s true. If it were indeed an H bomb, it would be the most efficient fussion we’ve ever seen, something many researchers don’t even believe is possible. So right now, all the evidence is pointing towards a fission bomb, what’s often called an atomic bomb. It’s possible that they did assemble an H bomb, but for some reason, it failed, or that they’re just bluffing. Even an atomic bomb would likely be enough to completely wipe an average city, so this shouldn’t be treated lightly. In fact, few things are as frightening as a nuclear war.
So here’s what we know so far:
- North Korea is conducting underground tests of bombs. We know this through a study of seismic waves.
- They say that future tests will include an open air test.
- They say they have an H bomb, but evidence indicates that they’ve “only” exploded an atomic bomb.
- Even such an atomic could lead to gargantuan explosions and cause unprecedented damage.
Seismologists Stumped by Mystery Shock after North Korea Nuclear Test
A second jolt felt minutes after this month's detonation continues to confound researchers
Eight-and-a-half minutes after North Korea set off a nuclear bomb on September 3, a second burst of energy shook the mountain where the test had just occurred. More than a week later, researchers are still puzzling over what caused that extra release of seismic energy—and what it says about North Korea’s nuclear-testing site, or the risks of a larger radiation leak. Monitoring stations in South Korea have already picked up minute levels of radiation from the test.
A number of theories have emerged to explain the second event, ranging from a tunnel collapse or a landslide to a splintering of the rock inside Mount Mantap, the testing site. But seismologists can’t agree and say that they may not get enough evidence to pin down the cause.
“This is an interesting mystery at this point,” says Göran Ekström, a seismologist at Columbia University in New York City.
The nature of the first seismic signal is clearer because it matches the profile of a bomb blast. The US Geological Survey (USGS) determined the magnitude of the seismic event associated with the nuclear explosion at 6.3, whereas the Comprehensive Nuclear-Test-Ban Treaty Organization (CTBTO) in Vienna calculated it at 6.1 on the basis of a separate analysis. The explosion was many times the size of past North Korean tests and was the largest seismic signal from a nuclear test ever detected by the international network of seismic monitoring stations used by the CTBTO.
The second event came 8.5 minutes later and registered as magnitude-4.1, reported the USGS. The agency suggested that it was associated with the test and may have been a “structural collapse”. The possibility that the smaller shock was caused by a tunnel collapse inside the testing site has dominated discussion in the media. But Paul Earle, a seismologist at the USGS, told Nature that was just one possibility that was raised in the immediate aftermath of the explosion. The USGS, he said, was “basing that on previous nuclear tests of comparable size that had a collapse”.
Possible signs of a collapse are visible on satellite images taken of the testing site, according to an analysis released on September 12 by 38 North, a partnership of the US-Korea Institute and the Johns Hopkins School of Advanced International Studies in Washington, DC.
But the seismic signal doesn’t match what would be expected from a collapse, says Lianxing Wen, a geophysicist at the State University of New York at Stony Brook. A collapse would produce mostly vertical movement of rock, but his own unpublished work suggests that the seismic clues point to a large horizontal movement as well, something he says would be more consistent with a landslide.
SLIDING SCALE
Although the satellite data do show a lot of landslides on Mount Mantap, other researchers argue that they could not have caused the magnitude-4.1 event. Much larger landslides, such as at Bingham Canyon mine in Utah in 2013, haven’t produced seismic signals close to that size, says Ekström.
He also argues that the seismic signals he has seen do not match the pattern expected from a landslide. Such an event would have longer-duration signals (matching the time that it takes rocks to fall down a slope) and fewer high-frequency waves (because the energy in a landslide is released more slowly than in earthquakes or explosions) than what was recorded in the North Korean event. He says that a collapse cannot yet be ruled out. The crater formed by a collapse sometimes does not become visible at the surface until much later.
Another theory comes from Ekström’s colleague at Columbia, seismologist Won-Young Kim. Kim rules out a collapse, a landslide and the possibility that there was an earthquake triggered by the explosion. He says that the seismic event was probably a rock burst—a violent fracturing of rock around one of the many tunnels under Mount Mantap. That could explain the frequency of the seismic waves, which were lower than an earthquake rupture but higher than a landslide, as well as the other features, he says.
The characterization of landslides and rock bursts could help researchers to assess how unstable Mantap is. Even if the whole mountain isn't going to collapse, as some have warned, subtler signs from landslides or rock bursts could indicate whether a major section of the mountain above the tunnels may have cracked. If so, that could lead to contamination of the mountainous area by radioactive material. “It is difficult to imagine how to contain that, given the altitude and remoteness of the place,” says Kim.
Stations outside of North Korea have started to detect radiation from the latest test. On September 13, the South Korean Nuclear Safety and Security Commission in Seoul announced that several ground- and sea-based monitoring stations downwind of the test site had detected the radioactive isotope xenon-133, an indicator of a nuclear test. However, no other isotopes were detected, preventing a determination of what type of bomb was used. It also did not indicate whether radiation is leaking from the site at a higher rate than expected, said Cheol-Su Kim, the head of the environmental radioactivity assessment department at the Korea Institute of Nuclear Safety in Daejeon, South Korea.
Based on South Korea's ground-based network of reporting stations, overall radiation levels there ranged from 50–300 nanosieverts per hour—no higher than the country's background level.
Seismologists Stumped by Mystery Shock after North Korea Nuclear Test
A second jolt felt minutes after this month's detonation continues to confound researchers
Eight-and-a-half minutes after North Korea set off a nuclear bomb on September 3, a second burst of energy shook the mountain where the test had just occurred. More than a week later, researchers are still puzzling over what caused that extra release of seismic energy—and what it says about North Korea’s nuclear-testing site, or the risks of a larger radiation leak. Monitoring stations in South Korea have already picked up minute levels of radiation from the test.
A number of theories have emerged to explain the second event, ranging from a tunnel collapse or a landslide to a splintering of the rock inside Mount Mantap, the testing site. But seismologists can’t agree and say that they may not get enough evidence to pin down the cause.
“This is an interesting mystery at this point,” says Göran Ekström, a seismologist at Columbia University in New York City.
The nature of the first seismic signal is clearer because it matches the profile of a bomb blast. The US Geological Survey (USGS) determined the magnitude of the seismic event associated with the nuclear explosion at 6.3, whereas the Comprehensive Nuclear-Test-Ban Treaty Organization (CTBTO) in Vienna calculated it at 6.1 on the basis of a separate analysis. The explosion was many times the size of past North Korean tests and was the largest seismic signal from a nuclear test ever detected by the international network of seismic monitoring stations used by the CTBTO.
The second event came 8.5 minutes later and registered as magnitude-4.1, reported the USGS. The agency suggested that it was associated with the test and may have been a “structural collapse”. The possibility that the smaller shock was caused by a tunnel collapse inside the testing site has dominated discussion in the media. But Paul Earle, a seismologist at the USGS, told Nature that was just one possibility that was raised in the immediate aftermath of the explosion. The USGS, he said, was “basing that on previous nuclear tests of comparable size that had a collapse”.
Possible signs of a collapse are visible on satellite images taken of the testing site, according to an analysis released on September 12 by 38 North, a partnership of the US-Korea Institute and the Johns Hopkins School of Advanced International Studies in Washington, DC.
But the seismic signal doesn’t match what would be expected from a collapse, says Lianxing Wen, a geophysicist at the State University of New York at Stony Brook. A collapse would produce mostly vertical movement of rock, but his own unpublished work suggests that the seismic clues point to a large horizontal movement as well, something he says would be more consistent with a landslide.
SLIDING SCALE
Although the satellite data do show a lot of landslides on Mount Mantap, other researchers argue that they could not have caused the magnitude-4.1 event. Much larger landslides, such as at Bingham Canyon mine in Utah in 2013, haven’t produced seismic signals close to that size, says Ekström.
He also argues that the seismic signals he has seen do not match the pattern expected from a landslide. Such an event would have longer-duration signals (matching the time that it takes rocks to fall down a slope) and fewer high-frequency waves (because the energy in a landslide is released more slowly than in earthquakes or explosions) than what was recorded in the North Korean event. He says that a collapse cannot yet be ruled out. The crater formed by a collapse sometimes does not become visible at the surface until much later.
Another theory comes from Ekström’s colleague at Columbia, seismologist Won-Young Kim. Kim rules out a collapse, a landslide and the possibility that there was an earthquake triggered by the explosion. He says that the seismic event was probably a rock burst—a violent fracturing of rock around one of the many tunnels under Mount Mantap. That could explain the frequency of the seismic waves, which were lower than an earthquake rupture but higher than a landslide, as well as the other features, he says.
The characterization of landslides and rock bursts could help researchers to assess how unstable Mantap is. Even if the whole mountain isn't going to collapse, as some have warned, subtler signs from landslides or rock bursts could indicate whether a major section of the mountain above the tunnels may have cracked. If so, that could lead to contamination of the mountainous area by radioactive material. “It is difficult to imagine how to contain that, given the altitude and remoteness of the place,” says Kim.
Stations outside of North Korea have started to detect radiation from the latest test. On September 13, the South Korean Nuclear Safety and Security Commission in Seoul announced that several ground- and sea-based monitoring stations downwind of the test site had detected the radioactive isotope xenon-133, an indicator of a nuclear test. However, no other isotopes were detected, preventing a determination of what type of bomb was used. It also did not indicate whether radiation is leaking from the site at a higher rate than expected, said Cheol-Su Kim, the head of the environmental radioactivity assessment department at the Korea Institute of Nuclear Safety in Daejeon, South Korea.
Based on South Korea's ground-based network of reporting stations, overall radiation levels there ranged from 50–300 nanosieverts per hour—no higher than the country's background level.
Seismologists Stumped by Mystery Shock after North Korea Nuclear Test
AZBeauty
Stop lyin' nicca.
NK is going to get blown off the planet. They need to calm the waters. Trump will nuke them into oblivion to distract from dealing with Russia investigation.
Hood Critic
The Power Circle
Mantis Toboggan M.D.
Drink wolf cola
We've been saying all year he's gonna start world war 3 to distract from Russia. Here it comes. Pretty sure their foreign minister also said they interpret his recent statements as a declaration of war.
I dont think he will. The stakes are too high to use fukking ww3 as a mere distraction. The country would revolt over bs like that
You're giving Americans too much credit.
Who would support ww3 over fukkin north korea?
mc_brew
#NotMyPresident
trumptards......Who would support ww3 over fukkin north korea?
I dont even think a majority of them would
One reason people voted for trump was because he said he wouldnt do foreign interventions and shyt which was a contrast to hillary
NYChase718
Veteran
And this bozo trump is worried about beefing with nfl sports players
Here's the thing. They talking big shyt but the reality is they are suffering economically like never before. They know there is no turning back with the tough talk. NK knows that US knows any preemptive strike will immediately put SK and Japan in jeopardy. So, this is just a war of words where NK knows there is no turning back.