World Bloggers

North Korea's nuclear bomb: Can we work out its power? The nuclear test that North Korea conducted on Sunday is thought to be the biggest ever conducted by Pyongyang. But what does this really mean and how will we find out more about the bomb? Physicist Ferenc Dalnoki-Veress explains. A nuclear explosion is an extremely large explosion, so large that it shakes the ground just as an earthquake does and is detected by seismic sensors thousands of kilometres away. The magnitude of the shaking is a measure of the immense energy released by the event. A parameter known as the body-wave magnitude (Mb) is used. This is not a linear scale. A magnitude-6 event, for example, releases 30 times more energy than one of magnitude 5. In all, 34 stations that are part of the Comprehensive Test Ban Treaty Organisation's (CTBTO) vast seismic monitoring network detected North Korea's explosion and it was so intense that it actually "saturated" the detectors . In other wo...