How can one tell a secret underground nuclear test from an earthquake

A new tool for distinguishing between naturally occurring earthquakes and nuclear tests with 99% accuracy has presented one research that saw the light of day.

Organizations such as the Comprehensive Nuclear-Test-Ban Treaty Organization today use global networks of instruments designed solely to detect nuclear tests. Among the instruments they use are seismometers which measure seismic waves. There are two types of seismic waves. Those that travel in waves in all directions and those that travel on the surface of the Earth.

By thousands earthquakes occur naturally every day on Earth, it's like looking for a needle in a haystack to find which earthquake was caused by a nuclear test. The scientists developed a more sophisticated method that calculates the ratio of the energy transmitted in waves traveling in all directions relative to the energy of surface waves. Natural earthquakes tend to have more surface energy than that produced by underground explosions.

However, this method also has its weaknesses, as it failed to detect North Korea's 2017 nuclear test, which produced significantly stronger surface waves as it took place inside a tunnel built into a mountain.

But now scientists study the displacement of rocks at the source of a seismic event, combining a complex statistical model to describe the different types of event. Thus, they found that there are significant differences between the sources of explosions and earthquakes, developing an improved method of categorizing the events.

Testing the new model on well-known nuclear tests and earthquakes in the western US, they saw that the model has a 99% recognition accuracy. The new model will be an important tool for global monitoring of nuclear testing and is critical to ensuring that governments are held accountable for the environmental and social impacts of nuclear testing.