The quake's center was 8 miles northeast of Christchurch with a depth of 6.3 miles, the U.S. Geological Survey reported.
There were no immediate reports of damage or casualties, the Australian News Network reported.
Christchurch, the largest city on New Zealand's South Island, is still recovering from a 6.3-magnitude earthquake in February that killed 182 people and caused about $15 billion in damage.
Beyonce flaunts bikini body, Blue Ivy in vacation pics
Jordana Brewster on Paul Walker: 'He was an enormous presence in my life'