The test was the 2,048th in the world. It recorded a seismic signal measuring 4.7 on the Richter scale. It took place 150-200 metres below the surface. The 1974 test took place 100 metres below ground level. The test released energy the equivalent of 53 kilotons of TNT.The 1974 test yielded 10 kilotons. The heat generated at the core of the hydrogen bomb at the time of the explosion was 7 times that of the sun’s core. The blast vaporised the device and rocks, and the rubble above collapsed sealing within it the radiation products.