North Korea's nuke tests are of seismic proportions

As North Korea continues to develop its nuclear program, ramping up tension around the globe, a group of scientists provides the world with information on the actual size and scope of nuke tests inside the hermit kingdom - and stands ready if Kim Jong Un plans another test soon.

As North Korea continues to develop its nuclear program, ramping up tension around the globe, a group of scientists is trying to determine the actual size and scope of the tests going on inside the hermit kingdom.

According to the Seismological Society of America, most of what the world knows about the country’s past nuclear tests comes directly from work by seismologists  -- scientists who study earthquakes and energy waves moving through the ground -- who are using a variety of tools to try and pinpoint the location, depth and size of these nuclear explosions. 

“There’s this building of knowledge that helps you understand the capabilities of a country like North Korea,” Delaine Reiter, a geophysicist with Weston Geophysical Corp. in Lexington, Mass told ScienceNews. “They’re not shy about broadcasting their testing, but they claim things Western scientists aren’t sure about. Was it as big as they claimed? We’re really interested in understanding that.”

“In the most basic terms, seismologists analyze the seismic waves recorded at various seismic stations, to identify the precise time that seismic energy arrives at each station, and how much energy is represented by the waves.” Richard Stead, a seismologist at Los Alamos National Laboratory told Fox News in an e-mail. 

“To determine the size of a nuclear test, seismologists use techniques that are basically the same as they use to determine the size of any seismic event, including earthquakes,” he added.  “In the most basic sense, we start by determining the magnitude.”

North Korea is the only country to perform nuclear tests this millennium, and all have taken place underground.  Stead says that means seismologists are “indeed essential” in confirming nuclear tests.

“There is a possibility that North Korea is likely to test its nuclear warhead and missile capabilities through a nuclear test with more explosive power,” South Korea’s Ministry of National Defense said in a report to the National Assembly Monday, according to  Yonhap News.

Forensic seismologists’ work can determine whether activity was natural or man-made, such as a nuclear test. One way to make that determination is the depth of the activity. Anything deeper than about 10 kilometers (6.2 miles) is almost certain to be natural.

In 2006, three years after the regime withdrew from the Treaty on the Nonproliferation of Nuclear Weapons, North Korea announced it had conducted an underground nuclear test in the northeastern part of the country.

Seismologists were able to confirm that claim by concluding the blast had come from shallow depths, no more than a few miles down, by analyzing scientific data gathered by monitoring stations in the area.  They were also able to narrow the location of the test and determine the explosion to be a small one, reportedly about one-fifteenth the size of the bomb the United Stated dropped on Hiroshima, Japan during World War II.

In 2009, 2013 and twice in 2016, Pyongyang set off more underground nuclear explosions, and seismologists concluded that the blasts were getting progressively larger. 

According to ScienceNews, the second 2016 blast was “deeply buried and hence probably at least as powerful as the Hiroshima bomb for it to register as a magnitude 5.2 earthquake.”

Stead said pinpointing the exact size and location of a nuke test is difficult to quantify. He added, “What is more important is whether the seismic results are sufficient for policy makers and decision makers in our nation's capital to act upon.  That is not a scientific determination.

“This information is used in many offices in the U.S. government. It obviously would have implication for national defense, diplomatic relations and decision-making up to and including the president.  Any government elected or appointed official, or civil servant whose duties have anything to do with nuclear tests and the implications foreign nuclear tests may have for national security, defense, international relations and other topics will likely be interested in the results of seismic analysis of the events.”

On September 10, 1996, the United Nations General Assembly adopted the Comprehensive Nuclear-Test-Ban Treaty (CTBT) which “bans nuclear explosions by everyone, everywhere on the Earth's surface, in the atmosphere, underwater and underground. The Treaty has a unique and comprehensive verification regime to make sure that no nuclear explosion goes undetected,” according to The Comprehensive Nuclear-Test-Ban Treaty Organization (CTBTO).

Part of that verification system is their International Monitoring System (IMS) which has over 300 monitoring facilities around the world, 170 of which are seismic stations similar to those that measure earthquakes.

The last declared North Korean nuclear test was detected at over 100 of the IMS seismic stations. It was reported that with current knowledge, the location of a nuclear test can be determined with very high confidence to within a few miles.

CTBTO said the 183 states that are signatories to the CTBT -- including the USA -- receive both the raw data from the IMS and the results of the analysis conducted by a small international staff of experts.  Some states augment this data and analysis with their own national sources and analysis by their own experts. 

This data and analysis can form a common basis for nations to use in political debate and multilateral decision making regarding possible violation of the treaty. 

According to the CTBTO, when North Korea tested in 2006, 2009 and 2013, the data was processed and distributed to their member states who “received information about the location, magnitude, time and depth of the tests within two hours – and before the actual test had been announced by North Korea.”