New Zealand rocked by strong aftershock
The South Island has seen hundreds of tremors, including a 6.3-magnitude quake, after the initial one struck after midnight on Nov.14.
The epicentre is northeast of Christchurch, near the town of Kaikoura which has been cut off by landslides.
A large river dammed up by a landslide also breached its banks, sending a "large wall of water" downstream.
Residents around the Clarence River - one of the largest on South Island - were being urged to move immediately to higher ground.
Military helicopters and a navy ship are being sent to evacuate more than a thousand people who remain stranded in Kaikoura.