Most powerful starquake

On 27 December 2004, a starquake on the ultra-compact stellar corpse SGR 1806-20, caused a flash of gamma rays equivalent to around 10,000 trillion trillion trillion watts in intensity. The stellar corpse, known as a magnetar, consists of a ball of neutrons some 20 km (12 miles) across, but with a mass similar to that of the Sun, and spinning once every 7.5 seconds. It lies around 50,000 light years away on the other side of our Milky Way galaxy. During this 'flash' of radiation, SGR 1806-20 released as much energy in one tenth of a second as the Sun does in 100,000 years. Magnetars are a rare type of neutron star with unusually strong magnetic fields. A magnetar could destroy the information on all the credit cards in the world at the distance of the Moon. If this event had occurred within ten light years of Earth, it could have resulted in a mass extinction.