The damage bill from New Zealand's Gisborne earthquake has topped $NZ45 million ($39.2 million) and is still rising.

The magnitude 6.8 earthquake, which struck the town on December 20, caused shops to collapse, roofs to fall in, felled power lines and opened up holes in roads.

Residential damage is estimated at $NZ24.2 million ($21 million) so far, with $NZ21 million ($18.3 million) identified in commercial damage and more than 5000 claims received, according to the Earthquake Commission.

Insurance Council of New Zealand CEO Chris Ryan told insuranceNEWS.com.au the cost has risen $NZ10 million ($8.7 million) in the last month and was likely to rise slightly before the March 20 cut-off date for claims.

He says some policyholders are yet to realise the full extent of the damage to their homes. "Earthquakes take a lot longer to calculate the cost of them than other natural disasters."

The issue will now be finding enough tradesmen to repair the damage.

"The key thing is we have been very well received by the community. What we feel is that the insurers have been a constructive force. We will now need some patience as repairs get under way."