I was about to tweet thoughts on the images released tonight, but that'll have to wait now. I wonder if this test will vent more than #4/#5.
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'Venting' refers to the release of radionuclides/contaiminants from an underground test. DPRK has been good at tamping its explosions down.
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Allowing careful venting would be one way for DPRK to allow US/int'l community to verify a fully-staged thermonuclear detonation.
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Some folks wondering how we know this is a test: quake occurred right on the half-hour mark UTC (like #4 & #5) and location is Punggye-ri.
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(PYT, North Korea's bespoke timezone, is half-hour off UTC and KST, so it's an on-the-hour test for them.)
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Back to venting Q: has serious drawbacks. Too much can cause serious environmental danger (piss off China) & reveal perhaps a bit too much.
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Hard problem. Deterrence may require them to get folks to stop laughing at "Mr. Peanut" by demonstrating a capability; did they do so?
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UPDATE: USGS estimate now up to M6.3. If it holds, would represent a *significantly* greater yield than previous 5 #NorthKorea tests.
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I'm going to guesstimate this is well into thermonuclear range. (Ceteris paribus for depth & a few other things.)
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Just for reference: 5.6 is ~100 kilotons. 6.3 is a megaton. Just using Mb=4.05+.75Log(W). YMMV 3/
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(Still early, but feels like we'll be debating whether North Korea tested a device capable of a 100s-of-kilotons yield or a megaton yield.)
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UPDATE: Japan Meteorological Agency puts the magnitude of the seismic event in #NorthKorea today at 6.1M. US/China have 6.3M.
Now is probably not a good time to mention that USG sources told me today that the most recent Hwasong-12 reentry vehicle survived to 1 km.
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UPDATE: Latest USGS technical data on today's seismic event near North Korea's nuclear testing site at Punggye-ri.
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Note: Reports of a second seismic event near Punggye-ri are unverified & false as far as I can tell. USGS still has one 6.3M event.
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That report seems to be based off a 4.6M event reported by the China Earthquake Administration at 0.0km depth. USGS still has nothing.
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. has been preparing for a possible DPRK thermonuclear test for a while now. Will have statement soon.
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Rough visualization of the terrain near the Punggye-ri test site where the detonation is suspected to have taken place per USGS data.
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China Earthquake Administration's 4.6M recording seems to concern a cave-in. This should be viewable via satellite.
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#BREAKING New 4.6 quake detected in North Korea due to 'cave in': China
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*If* this is true, their attempts at venting prevention may have failed entirely and USAF WC-135s should be able to pick up quite a bit.
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I'm still rather skeptical that there was a cave-in that'd generate a 4.6M event and USGS would have zilch. Tread carefully for now.
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FWIW, 's model of the Punggye-ri site suggested that a few hundred kilotons would be safe.
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Replying to @ArmsControlWonk
2. North Korea could safely conduct much larger thermonuclear explosions under these mountains, up to a few hundred kilotons. (12/16)
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Of course, with 6.1-6.3M, we're probably well in the near-megaton or megaton range. That's why a more serious cave-in might be plausible.
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(Again: depending on depth and several other variables. Could be lower yield than that too.)
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Important. As suspected, second 4.6M seismic event reported first by China Earthquake Admin likely incorrect.
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SK Geo Survey said another, follow-up quake detected at 4.6 Richter scale. It's taking that back: it never happened
twitter.com/yonhaptweet/st
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(Seismic events are measured on the moment magnitude scale today; not the Richter scale.)
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This is likely cautionary, but worth watching closely. #China's reaction in immediate aftermath will be important. twitter.com/chadocl/status
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Also, not to make a bad day worse, but this KCNA line really stuck with me. They might need a September 9 activity.
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"He watched an H-bomb loaded into new ICBM." twitter.com/DaveSchmerler/
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Will sleep soon, but if all this makes you want a military response against North Korea, consider the following:
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An interesting assessment here: would be downward from a fully staged thermonuclear device, but usable today.
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It is probably a fieldable boosted test that can indeed be put on the Hwasong-14! Very scary! We are in new territory! @ArmsControlWonk
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Well, guess I'm staying up a little longer.
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(URGENT) N. Korea says it will make special announcement at 15:00 (Pyongyang Time) english.yonhapnews.co.kr/news/2017/09/0
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#NorthKorea's official announcement about tonight's test should be broadcast on KCTV when this tweet is 49 minutes old.
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Early South Korean yield estimate. Would easily put this in low-100s of kilotons range.
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S. Korean authorities now confirming that this nuclear test was 9.8 times as powerful as last year's test, the previous biggest. twitter.com/yonhaptweet/st
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Seismic data analysis comparing waveforms to demonstrate similarities of tonight's event w/ a known DPRK nuke test.
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Comparisons of nearby seismic signal for today's M6.3 & last M5.3 nuclear test by @drrocks1982 & 2013/2016 tests by @AKearthquake
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Technical data of secondary seismic event—labelled as "Collapse" so not a second test. Measured a 0.0 km depth.
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This may be a normal & expected side-effect of a test of this magnitude. Or it could be unforeseen & affect venting. twitter.com/srianjalidevi7
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(Seems unlikely that this is the *same* event China Earthquake Admin had reported earlier and retracted.)
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