Figures released by an electronic transaction processing company suggest as many as 56,000 people may have fled Christchurch in the days after February's earthquake.
Paymark cannot access personal information, but says 393,422 cards were used in Christchurch in the period before the quake struck.
Over the 12 days following the quake, 56,326 of the cards were used outside of Christchurch.
More than 10,000 were used in the Auckland and Northland regions, and a further 10,000 were used in the Canterbury region excluding Christchurch.
Seven thousand of the cards were used in Otago, while more than 3000 were used in Wellington.
The figures suggest over the nine weeks following the quake as many as 21,000 people may have returned to Christchurch.
On 1 May, almost 35,000 cards were still being used outside Christchurch city.