A strong earthquake has struck Christchurch in New Zealand and there are reports of major damage in the city. The US Geological Survey says the quake was 6.3 in magnitude and struck at a shallow depth of just four kilometres. It says the quake hit shortly before 12.50 pm local time, just five kilometres to the north-west of the city. All phone lines to the city on the South Island are down and some power has been cut. A New Zealand Herald reporter says the quake lasted for about a minute and was extremely violent. The Herald's website says buildings shook back and forth, roads have cracked and water supply pipes have burst, flooding streets. The website says many people are now out on the streets.