What is ‘decoupling’ and how does it work?

• ‘Decoupling’ is a technique used to reduce the intensity of an underground nuclear explosion. When a country conducts a nuclear test, the seismic waves generated from it are immediately detected by seismic stations around the world. But in decoupling technique, the nuclear device is placed in the middle of a very large and empty underground cavity.
• When an explosion occurs, that empty space acts like a shock absorber. Due to this the movement in the ground is greatly reduced. Experts say that with this technology, even a big explosion can be shown very small in front of the world, due to which the scientists reading the seismic data can get confused whether it is a small explosion or an ordinary earthquake.

How did Kazakhstan’s data expose China?

China violated international rules

Most of the countries in the world follow the ‘Comprehensive Nuclear Test Ban Treaty’ (CTBT), which prohibits any kind of nuclear explosion. However, both China and America have signed this treaty but have not got it passed (ratified) by their parliament. Despite this, both countries claim to adhere to the ‘Zero Yield’ standard, which means they will not conduct any test that releases nuclear energy. If America’s claim of ‘decoupling’ proves true, it means that China has broken international trust.