The Christchurch earthquake most notably refers to two major events in New Zealand’s Canterbury region:

• The Darfield event: A magnitude 7.1 earthquake occurred at 4:35 am on September 4, 2010, located about 40 km west of Christchurch on the Greendale Fault. This was the principal quake that triggered extensive aftershocks and widespread damage across the city and surrounding areas.
• The major aftershock: On February 22, 2011, at 12:51 pm local time, a magnitude roughly 6.2 (often cited as 6.3) earthquake struck near the central city of Christchurch, causing catastrophic damage, particularly in the city center and eastern suburbs, and resulting in a high death toll of 185 people. This event is considered a significant aftershock of the 2010 sequence but felt as a separate, major earthquake in its own right.

If you’re looking for precise dates and times:

• Darfield (Canterbury) earthquake: September 4, 2010, 4:35 am local time.
• Christchurch February 2011 earthquake: February 22, 2011, around 12:51 pm local time.

If you’d like, I can provide a concise timeline of the 2010–2011 Canterbury earthquake sequence and include impact highlights.