The era of nuclear secrecy has ended, Now nuclear tests can be accurately monitored

It was previously difficult to distinguish between nuclear explosions and earthquakes, but a recent study suggests that secret underground nuclear testing could now become a thing of the past thanks to major scientific advances in identification methods.

Distinguishing between underground explosions and naturally occurring earthquakes is one of the fundamental challenges of monitoring nuclear explosions, as explosions and earthquakes can generate seismic energy with similar characteristics.

Earth scientists and statisticians say they can now tell whether a nuclear explosion has occurred with up to 99% accuracy.

Among the things that prompted great international efforts to develop the ability to monitor nuclear tests were the initial nuclear weapons tests in the 1940s, which then spread throughout the world. 75% of these tests were conducted underground, and were visible through seismic waves generated by The explosion, which travels great distances and can be detected using seismometers, but it was difficult to distinguish whether they were explosions or earthquakes.

Global seismic networks, such as the International Monitoring System of the Comprehensive Nuclear-Test-Ban Treaty Organization, monitor underground nuclear explosions around the world, providing critical information that cannot easily be estimated using other geophysical methods.

The technology used

This method for distinguishing between explosions and earthquakes relies on moment tensors. Moment tensors provide a physics-based classification tool for characterizing different seismic sources, and have enabled the emergence of new techniques for distinguishing between earthquakes and explosions.

 

The mathematical model used in this study was built by analyzing physical differences in the deformation pattern of rocks at the source of nuclear explosions and earthquakes, allowing experts to determine whether this event was an earthquake or an explosion.

Dr. Hoggard, one of the researchers behind the study, says that by using some advanced mathematical methods and statistical processing, they were able to improve the classification success rate from 82 to 99%, relying on a data set of 140 known nuclear tests in the United States using their own momentum tensors.

It also does not require any new equipment and does not require the use of satellites, only standard seismic data can be used.

The research was conducted by a team of geoscientists and statisticians working at the Australian National University and the Los Alamos Government Research Laboratory in the United States.

mistake percentage

This mathematical model only misclassified 17 events out of a total of 1,289 explosions or earthquakes.

Of the 140 nuclear explosions included in the study, the only two that were incorrectly classified were Crowdy's underground nuclear test on May 5, 1983, and the chemical explosion on July 20, 2018. Applying this method to nuclear tests from 2006 Even 2017 in the Democratic People's Republic of Korea resulted in a 100% accurate classification.

Therefore, this method can achieve classification rates of up to 99% accuracy for explosions.

Can nuclear explosions be detected anywhere?

The development of the method for distinguishing between earthquakes and explosions using the moment tensor in this study was based on data from earthquakes and explosions that occurred in the western United States and indexed in the “Bassianos and Chiang 2021” event catalogs (a catalog that includes moment tensors for events that occurred in the western United States), so it is best to evaluate its success in classifying Events at other locations.

Although researchers expect the physical mechanisms occurring in the source region of explosions and earthquakes to remain consistent across different spatial environments, there are two issues that may affect the success rate of classification:

 The first problem is that in many regions catalogs of explosions and earthquakes are not available, and therefore one is limited to using the standards mentioned in the study that were obtained from catalogs of events in Western America.

 The second problem is that local seismograph measurements are likely to be less accurate in many areas, which raises doubts about the moment tensors that will be included in the scheme presented in the study.

A full assessment of the impact of these issues on classification success rates requires further research, but preliminary insight into the method's applicability in other regions can be gained by evaluating its ability to identify known nuclear tests conducted outside the United States.

The study was applied to the six announced nuclear tests that were conducted in North Korea between 2006 and 2017, in addition to the meltdown that occurred immediately after the 2017 test. It was also applied to the two earthquakes that occurred in 2016 and 2017 in South Korea. For all of these events, special moment tensors were published. With it, using these moment tensors and applying them to this study, they accurately identified the nuclear tests as explosions, while they accurately identified the other two events in South Korea as earthquakes rather than explosions.

Therefore, the method seems suitable for classifying events and explosions in areas other than the study area.