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North Korea’s 24-Hour Nuclear Cycle
How to track a nuclear explosion in the Twitter era.
North Korea’s nuclear test has me thinking a lot about time. Maybe it’s just because Ben Pauker and Cameron Abadi, my illustrious FP editors, have been breathing down my neck about filing this piece. But I don’t think that’s it. I just can’t get over how quickly the world learned that something had happened in North Korea — and how quickly the world demanded to know exactly what it was.
In 1993, two researchers from London’s VERTIC think tank — Vipin Gupta and Philip McNab — made headlines when they used commercial satellite imagery and seismic networks to detect and characterize a Chinese nuclear test, and announce it before the Chinese government did. Gupta and McNab only pulled this off after a huge production, including the creation of an elaborate notification system using their home computers after a plan to stay online in shifts throughout the night was waylaid by a flu outbreak.
In 2016, by contrast, I was sitting at Doris Day’s Cypress Inn, finishing up a cocktail when my smart phone started buzzing. (A Corpse Reviver No. 2, if you must know.) That’s how I learned that seismic stations had detected interesting things at North Korea’s nuclear test site. A few days before, after noticing interesting things in satellite images, I had set up email notifications with the U.S. Geological Survey, which is responsible for tracking earthquakes, and a website a friend created to aggregate regional seismic data. I had a real-time feed that nicely alerted me when things started to shake.
At first, it wasn’t even clear what I was looking at — and that wasn’t just the cocktail talking. The initial USGS readings did not look like a nuclear test. While the event was on the hour — 10:00 a.m. sharp, DPRK time, suggesting a man-made event conducted according to a schedule — USGS placed the epicenter several kilometers off the test site and estimated the depth at 10 kilometers, way too deep for a nuclear test. A few minutes later, the Chinese seismic network placed the event closer to the test site and suggested a shallow explosion. It’s nice to have competing sources of data!
It’s worth remarking on the weirdness of this process. We’ve gone from Gupta and McNab trying to stay awake in shifts to catch a test in China, to me lounging at a bar waiting for emails from one of several open seismic networks. The Twitter hive-mind knew it was a nuclear test well before North Korea released its grandiloquent announcement about testing an H-bomb. A few hours later, at the more leisurely pace befitting an international organization, the Preparatory Commission for the Comprehensive Nuclear-Test-Ban Treaty Organization announced that 27 of its seismic stations had detected the event.
But just because we knew immediately that something happened, doesn’t mean we knew what had happened. Obviously, the big question everyone wants an answer to is: Was it really an H-bomb?
It’s still strange to me that we expect instant replies to complicated questions that aren’t entirely under our control to answer. In 2013, it took 55 days for radioactive gases from North Korea’s nuclear test to escape and drift over a sampling station in Japan. No release was even detected after North Korea’s 2009 nuclear test. Mother Earth does not seem to care about the 24-hour news cycle.
There are some things we can say about this week’s event. It looks like an explosion, not an earthquake, and we have some sense of how big it was. You measure the size like you do an earthquake; think of the Richter scale. Estimates of the magnitude of the body wave range from 4.9 to 5.1, though not all the scales are identical. Depending on variations in geology, that allows us to make an approximate estimate of the size of the explosion: It was probably around 10 kilotons. Maybe a little more, maybe a little less. But not one kiloton and definitely not 100.
At that level of explosive power, the device was probably not a canonical “H-bomb,” which usually means a two-stage nuclear device in which a primary fission bomb produces radiation that implodes a secondary device that contains fusion fuel. The first thermonuclear weapon used cryogenic liquid deuterium — an isotope of hydrogen. Hence, the H-bomb. If North Korea were to successfully build a two-stage thermonuclear weapon, it would likely have a yield of hundreds of kilotons, if not a megaton or more.
But the term hydrogen bomb can also be used to refer to something equally interesting — boosting. Scientists can “boost” the yield of a fission device by injecting a gas of deuterium and tritium into it. Like deuterium, tritium is an isotope of hydrogen — so this is also considered a sort of H-bomb. There are a number of advantages of “boosting” a fission device, but in general boosting allows one to make more efficient use of nuclear material — more bang for your buck, so to speak. This is an enormous advantage, particularly if one wants to make increasingly compact nuclear warheads to arm missiles. And that is something that would very much interest North Korea.
As I have written before, the North Koreans seem to have placed an emphasis on developing nuclear weapons small enough to fit atop their ballistic missiles, including the various ICBM prototypes they have paraded through Pyongyang in recent years. Those missiles are likely to be inaccurate, so North Korea has to find a way to reduce the size of its nuclear weapons without sacrificing yield. Boosting is a good way to do that.
That brings me back to time. There is this strange thing that happens when North Korea conducts a nuclear test or launches a ballistic missile. While we get very angry, we quickly slip into a kind of paralysis. We act as though it is now too late to do anything. Colin Powell once famously asked why it mattered if North Korea continued building nuclear weapons once they already had a handful. And the Obama administration, after a piddling attempt at diplomacy, has settled into a policy that is euphemistically called “strategic patience” — a fancy way of saying it won’t do anything. There is, I think, a mistaken assumption that the North Koreans, having built a few crude bombs, will be satisfied and turn their attentions elsewhere. It is unpleasant, but we can hold our noses while we wait for them to collapse.
Someone has other ideas, however. North Korea isn’t getting bored with its nuclear program. Maybe it started as a bargaining chip, but the juche bomb has become a central element in the story that Kim Jong Un’s lackeys tell the Korean people about why he should get to run the country. Over time, North Korea has gone from some plutonium to a crude bomb to increasingly more advanced designs. It doesn’t take an enormous amount of foresight or open-source information to see that this story ends in a staged thermonuclear weapon. If North Korea doesn’t have an honest-to-f’in-goodness H-bomb yet, it will sooner or later — unless we persuade them otherwise.
That brings us back to the same old recommendations, about as exciting as “eat your vegetables.” I’ll spare you the lecture that the late Stephen Bosworth — a career diplomat and North Korea envoy for the Obama administration, who died this week — would have given about the importance of trying to find a diplomatic solution, no matter how unlikely that seems. But in exchange, do me one favor: Don’t pretend that this problem is going to solve itself.
Photo credit: Jung Yeon-Je/AFP/Getty Images