North Korea withdrew from the Treaty on the Non-Proliferation of Nuclear Weapons in 2003. It subsequently developed nuclear weapons, with five underground nuclear tests culminating in a suspected thermonuclear explosion (a hydrogen bomb) on 3 September 2017. Now a team of scientists, led by Dr K. M. Sreejith of the Space Applications Centre, Indian Space Research Organisation (ISRO), have used satellite data to augment measurements of tests on the ground. The researchers find that the most recent test shifted the ground by a few metres, and estimate it to be equivalent to 17 times the size of the bomb dropped on Hiroshima in 1945. The new work appears in a paper in Geophysical Journal International, a publication of the Royal Astronomical Society.To read more, click here.