Why did the Christchurch earthquake (2011) in New Zealand cause much more damage than the larger Canterbury earthquake (2010) ?

It was closer to a large city with buildings that had been damaged by the earlier earthquake

Explanation:

The city Christchurch, of New Zealand, witnessed several earthquakes between 2010-2011. On 4th September 2010, the city witnessed an earthquake of 7.0-7.1 magnitude. But, the most damaging earthquake in the series was that occurred at 12:51 PM on 22nd February 2011. The magnitude of this earthquake was 6.3. The earthquake was most damaging of all because the earthquake was the shallow one. The earthquake took place four kilometers below the ground in 2011 whereas, in 2010, it was ten kilometers below the ground. Because of this, the earthquake of 2011 was most damaging. The other reason for this damage was that the earthquake of 2010 took place in the farmland, the earthquake of 2011 took place near the city area and was close to the larger buildings.