Okwudiri Straightman Nwali

The North Korean bomb test that caused tremors in China: Mystery over rogue nation's 'hydrogen' explosion that split children's playground and shook roads and buildings hundreds of miles away

North Korea claimed to have executed a successful hydrogen bomb explosion (bottom left) which triggered a 5.1 magnitude earthquake that was felt for miles, but its opponents and nuclear experts are dubious. Analysts and foreign officials insist the size of the explosion and resulting tremors were far too small to have come from such a device. Hydrogen bombs (top left, explainer graphic) can generate vast and violent amounts of energy through nuclear fission - the splitting of atoms - followed by fusion - the combining of atoms. They are hundreds of times more powerful than atom bombs, such as the ones that flattened Hiroshima and Nagasaki. North Korea said the H-bomb was miniaturised, meaning it could be carried out missiles that would pose a new threat to the United States and its regional allies. Pyongyang has developed the Taepodong-2 (top right), a long-range missile with an estimated range of around 3,700 miles. The alleged H-bomb test, which comes after weeks of speculation that leader Kim Jong Un (bottom right) had illegally developed such a weapon, has been condemned by countries around the world, including its allies China and Russia.