Actually it were two powerful earthquakes in Christchurch today. It happened less in a year from last large earthquake in Christchurch on February 22 this year. In this video possible to see what was happening.
In case you are planning your travel to New Zealand, you should check what situation is in Christchurch area as it can be not safe to enter that area.
Check this map www.christchurchquakemap.co.nz/today what is happening there right now.
For latest news and updates check live coverage of NZ earthquake on ABC News 24 www.abc.net.au/news/abcnews24