Major landslides are blocking the roads in and out of Kaikoura, which is also without power and phone services.
The town was hard hit by a 7.5 magnitude quake, which struck near Hanmer Springs at 12.02am yesterday. It was 16km deep and has been followed by more than 800 aftershocks.
Dozens of helicopters, including four Defence Force NH90s, have been ferrying people and supplies in and out of the town today.
RNZ reporter, Tim Graham is there and has been talking to locals.