Dozens of helicopters are being drafted in to move residents and tourists from the seaside town of Kaikoura.
It is a whale-watching resort that was hit hard and cut off by the quake.
Hundreds of aftershocks have rocked the area, with major road and rail links still severed.
Two people were killed in the 7.5 magnitude earthquake and billions of dollars of damage was caused.
It is estimated that up to 1,200 tourists are among those stranded by the quake which has been blamed for causing "utter devastation" on the north-eastern coast of the South Island.
A navy ship is heading towards Kaikoura, whose population of 2,000 people bore the worst impact of the quake. But it will not arrive until Wednesday.
Huge landslides have severed road and rail links to the town, with police warning that water and electricity supplies are running out. Hundreds of people remain in evacuation shelters.
Prime Minister John Key predicted the quake repair bill is likely to run into billions of dollars and the top priority was to provide desperately-needed supplies to Kaikoura.
The South Island has seen hundreds of tremors, including a 6.3-magnitude quake, after the initial one struck after midnight on Monday, north-east of Christchurch.