Christchurch was rocked by a 7.1 magnitude earthquake which caused widespread damage and left thousands without power and water as night falls.The second biggest city was also hit by a series of major aftershocks.Prime Minister John Key, who saw first-hand the devastation across Christchurch, said it was a miracle more people weren't killed."It's a miracle there where so few casualties*."Much of the ruined city remains cordoned off* by police following the devastating earthquake.Christchurch Mayor Bob Parker has requested the army to help provide safety and security in the city in the wake* of the country's most damaging earthquake since the 1931 Napier disaster. He also asked people to conserve* water and keep boiling water for drinking, not to flush the toilet unless necessary, and not to ''rubberneck*'' because it was important roads were clear for vital services.The mayor urged people to check on* their neighbours. "The most important thing is that there has been no loss of life.''