About 150,000 to 200,000 people felt strong or very strong shaking, CNN meteorologist Derek Van Dam said.
The quake was centered about 17 kilometers (10 miles) east of Christchurch, which suffered a catastrophic temblor in 2011 that killed at least 185 people
Almost exactly five years later, the quake Sunday caused a cliff to crumble near Taylor's Mistake bay.
Parts of the cliff retreated 5 meters (16 feet), geotechnical engineer Jan Kupec Linz told CNN affiliate TVNZ
Some narrowly escaped the collapse.
"I'd taken five of my rookies to do some cliff work and some cliff jumping," Craig Jamison, a member of the Taylor's Mistake Surf Life Saving Club
, told the affiliate.
"When I look up I see three of them standing in the cave, and then a whole sheet of rock fell down over them."
But they were lucky; no one was seriously injured.
Elsewhere near Christchurch, the quake hurled items off store shelves. Heavy sport-utility vehicles shook like gelatin.
"We've definitely had a spike in calls shortly after the quake involving what we call fainting type events, chest pain, shortness of breath and falls," local ambulance manager Kerry Mitchell told TVNZ.
While no casualties were reported, officials are concerned about possible aftershocks.