An upgraded 7.5 magnitude earthquake has struck 20km south-east of Hanmer Springs, Geonet says.
Many people evacuated from the north Canterbury town of Kaiapoi due to the tsunami risk have hunkered down in their vehicles at the Pak n'Save carpark in a nearby town.
The Herald understands the carpark at the Rangiora supermarket, about 11km inland from Kaiapoi, is full of people seeking asafe place to park, petrol and supplies.
The supermarket is yet to open for business, but staff are doing their bit to help fleeing residents.
Kineta Booker has spent much of the night in her car with her husband and toddler.
The couple went to get petrol from the self-service pumps after leaving their home near the coast.
Booker said out of nowhere a team of supermarket staff came out and started checking on people in the carpark.
"My car was on empty so we went searching," she said.
"Everyone was queued up and these angels came out of nowhere and they were making sure everyone was doing okay, even while they're probably freaking out themselves. It was so awesome."