Deterrence
Re: Deterrence
No more low intensity seismic shocks in Pak in the past couple of months ?
Re: Deterrence
The frequency’s the same as before — nothing unusual. They’ve just dropped out of the news cycle because there’s no real significance to report (as have been posted a few times here in details).
Re: Deterrence
https://www.ndtv.com/world-news/china-c ... s-10966774
No idea about the veracity of this claim as the US may just be trying to do unglee and in all likelihood doing the same thing or sub critical tests.
From the article:
No idea about the veracity of this claim as the US may just be trying to do unglee and in all likelihood doing the same thing or sub critical tests.
From the article:
From AI:"China has conducted nuclear explosive tests, including preparing for tests with designated yields in the hundreds of tons... China has used decoupling - a method to decrease the effectiveness of seismic monitoring - to hide its activities from the world.
How is this any different from how India tested or any underground nuclear test?Overview of Nuclear Testing by Decoupling
Decoupling is a method used in nuclear testing to reduce the seismic signals generated by an explosion. This technique allows a country to conduct a nuclear test while minimizing detection by monitoring systems.
How Decoupling Works
Mechanism
Underground Cavities: A nuclear device is detonated in a large, deeply buried cavity. This setup absorbs much of the explosive energy, which reduces the seismic waves that escape into the Earth.
Seismic Wave Reduction: The energy from the explosion increases gas pressure in the cavity, which can significantly muffle the seismic signals. This makes it harder for monitoring stations to detect the test.
Re: Deterrence
The American need to involve ALL nuclear powers in Nuclear Arms Limitation talks is the driver for all current noise.
Re: Deterrence
Decoupling isn’t magic stealth. It can reduce seismic signals by maybe 10–50× for very low-yield shots, not make “hundreds of tons” invisible. Even a well-decoupled test at that scale should show up on regional/CTBTO seismic networks, and usually radionuclide stations too.
India’s tests weren’t decoupled and were detected immediately — so comparing the two actually weakens the claim.
Subcritical tests are a different beast altogether (zero yield, legal under CTBT, done by everyone including the US).
My take: Without public seismic or xenon data, this looks more like political signaling than a demonstrated nuclear test.
India’s tests weren’t decoupled and were detected immediately — so comparing the two actually weakens the claim.
Subcritical tests are a different beast altogether (zero yield, legal under CTBT, done by everyone including the US).
My take: Without public seismic or xenon data, this looks more like political signaling than a demonstrated nuclear test.
Re: Deterrence
AmberG : is it possible to provide a brief semi technical explanation of what is decoupling and how it differs from an underground test?
The AI explanation is either vague or wrong…
The AI explanation is either vague or wrong…
Re: Deterrence
Yes, may be important technical distinction being blurred there.
Decoupling is fairly known concept - detonating a device in a large underground cavity reduces seismic coupling to surrounding rock. In ideal conditions, it can suppress seismic amplitudes by roughly a factor of 10–70, depending on geology and cavity size. (Decoupling involves detonating a device in a large underground cavity. The air or empty space inside the cavity acts as a cushion, ensuring the pressure on the surrounding rock walls remains below its elastic limit)
But It does not eliminate seismic signals. ( “Decoupling” isn’t invisibility cloak)
- It works best only for very low-yield tests (tens of tons TNT equivalent).
It requires large, carefully engineered cavities, which themselves leave observable signatures (tunneling, spoil piles, etc).
Most importantly for “hundreds of tons” yield, even a well-decoupled test would still be detectable by regional and teleseismic networks, especially with today’s IMS density.
So the phrase “hide its activities from the world” physics wise does not make sense.
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India’s 1974 and 1998 tests were fully coupled underground tests, not decoupled cavity shots. produced clear seismic signals, detected internationally within minutes.
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Subcritical tests are a red herring herent they produce zero nuclear yield by definition. (They are conducted by the US, Russia, China--including at Nevada and Lop Nur - are not prohibited under the CTBT.
If the activity were subcritical, seismic signature (and radio nuclei tests) will be a little different from nuclear explosion.
Calling it a “nuclear explosive test” would be technically incorrect.
-- What I think-
- No nuclear test — claim is political signaling (most likely).
(or Subcritical experiments being rhetorically upgraded.
(or Very low-yield hydronuclear experiment (borderline, still hard to hide). or Hundreds-of-tons decoupled test — least consistent with available evidence)
In short -
Decoupling is real, but it doesn’t make nuclear tests invisible — especially not at “hundreds of tons.”
India’s underground tests were fully detectable and fundamentally different.
Without open seismic or radionuclide data, the claim remains political, not scientific.
A good reference for decoupling and other such topics for those with detailed technical detailals:
The Comprehensive Nuclear Test Ban Treaty: Technical Issues for the United States (2012)
Chapter: APPENDIX E Dealing with Evasive Underground Nuclear Testing
(I think you can access the appendix E at:
https://www.nationalacademies.org/read/12849/chapter/13)
Last edited by Amber G. on 08 Feb 2026 04:10, edited 1 time in total.
Re: Deterrence
https://link.springer.com/chapter/10.10 ... -0419-7_17
Dealing with Decoupled Nuclear Explosions under a Comprehensive Test Ban Treaty
The detonation of nuclear explosions in huge underground cavities so as to muffle or decouple the seismic waves they generated has been debated for more than 35 years. This paper reviews the history of the decoupling concept, assesses what countries have the technological capabilities to carry out such a test of a given yield, and evaluates several decoupling scenarios. I conclude that testing with huge decoupling factors, DF, is feasible for yields of a few kilotons (kt) or larger only in cavities in salt domes. Past nuclear explosions conducted in salt that are large enough for the full decoupling of explosions with yields ≥ 0.5 kt are concentrated in only a few areas of Kazakhstan and Russia. The existence of all cavities of that size that were created by past explosions is known since the events that created those cavities must be at least 20 times larger in yield than the size of a fully decoupled event that can be detonated in them. Monitoring of cavities created in that way that may remain standing should be relatively easy at the 1 kt level if appropriate verification measures are put in place. While large cavities can be created in salt by solution mining, no country is known to have evacuated the brine from such a cavity and then conducted a decoupled nuclear explosion in it. Air-filled cavities in salt suitable for significant decoupled testing are stable over only a very narrow range of depths from about 200 m to a maximum of 900 to 1300 m. Most areas of thick salt deposits in the Former Soviet Union and the U.S. are typified by efficient transmission for seismic waves and low natural seismic activity. The scaled cavity radius of 20 m cited in the literature for full decoupling in granite is poorly determined, probably is too small, and has resulted in overestimates of the potential to employ cavities in hard rock for decoupled nuclear testing. For cavities in hard rock, lack of any known experience in conducting decoupled nuclear testing in them, insuring containment in the presence of large differences in principal stresses and the presence of joints and other inhomogeneities on a scale of 1 to 100 m, and the excavation of such a large cavity without being detected are factors that make clandestine decoupled testing of a few kt or larger very unlikely for sites in hard rock, even for countries with considerable testing experience. Decoupled testing of large DF in any media at such yields by countries lacking containment experience would be difficult to carry out in secrecy.
Dealing with Decoupled Nuclear Explosions under a Comprehensive Test Ban Treaty
The detonation of nuclear explosions in huge underground cavities so as to muffle or decouple the seismic waves they generated has been debated for more than 35 years. This paper reviews the history of the decoupling concept, assesses what countries have the technological capabilities to carry out such a test of a given yield, and evaluates several decoupling scenarios. I conclude that testing with huge decoupling factors, DF, is feasible for yields of a few kilotons (kt) or larger only in cavities in salt domes. Past nuclear explosions conducted in salt that are large enough for the full decoupling of explosions with yields ≥ 0.5 kt are concentrated in only a few areas of Kazakhstan and Russia. The existence of all cavities of that size that were created by past explosions is known since the events that created those cavities must be at least 20 times larger in yield than the size of a fully decoupled event that can be detonated in them. Monitoring of cavities created in that way that may remain standing should be relatively easy at the 1 kt level if appropriate verification measures are put in place. While large cavities can be created in salt by solution mining, no country is known to have evacuated the brine from such a cavity and then conducted a decoupled nuclear explosion in it. Air-filled cavities in salt suitable for significant decoupled testing are stable over only a very narrow range of depths from about 200 m to a maximum of 900 to 1300 m. Most areas of thick salt deposits in the Former Soviet Union and the U.S. are typified by efficient transmission for seismic waves and low natural seismic activity. The scaled cavity radius of 20 m cited in the literature for full decoupling in granite is poorly determined, probably is too small, and has resulted in overestimates of the potential to employ cavities in hard rock for decoupled nuclear testing. For cavities in hard rock, lack of any known experience in conducting decoupled nuclear testing in them, insuring containment in the presence of large differences in principal stresses and the presence of joints and other inhomogeneities on a scale of 1 to 100 m, and the excavation of such a large cavity without being detected are factors that make clandestine decoupled testing of a few kt or larger very unlikely for sites in hard rock, even for countries with considerable testing experience. Decoupled testing of large DF in any media at such yields by countries lacking containment experience would be difficult to carry out in secrecy.