If a major earthquake were to strike Wellington it could cost almost $40 billion, a council report says.

The report, which will go to the council's strategy and policy committee next week, also raised concerns about the major routes in and out of the capital which could be blocked if unreinforced buildings fell in a quake, Radio New Zealand reported.

The city has 435 buildings with unreinforced masonry, 166 of which are heritage buildings, and could block vital roads leading in and out of the city.

Communications and utilities services are also vulnerable, the report said.


Earthquake resilience programme director Neville Brown told Radio New Zealand the report sought to illustrate the size of the threat so the city could prepare.

Mr Brown said a rebuild of Wellington after a major earthquake could cost around $37 billion, nearly twice the $20 billion it is estimated the Christchurch rebuild will cost.

"I should stress that it is really an assessment to try to put a quantum around the size of the issue the city faces."

Councillor Iona Pannett told Radio New Zealand identifying unreinforced masonry buildings was a priority and the council was looking to work with building owners to undertake earthquake strengthening.

The council is looking to help with financing earthquake strengthening, including borrowing funds which would be paid back through rates, and wants the central Government to apply tax rebates to earthquake strengthening work.

"The risk to Wellington has not changed because of there has been a massive earthquake in Christchurch, but the perception of risk has changed and the understanding that maybe we are not as prepared as we need to be," Ms Pannett said.