Quake-hit Christchurch residents will this week learn which areas of the New Zealand city must be abandoned because the ground has become too unstable to rebuild, officials said Wednesday.

As aftershocks continued to rattle the city, Earthquake Recovery Minister Gerry Brownlee said geotechnical data, which will determine the fate of thousands of homes, would be released on Thursday.

"This announcement will provide some certainty for residents in the worst-affected areas and will give them options for their immediate future," Brownlee said in a statement.

"We will be releasing the most up-to-date information we have about the state of the land in greater Christchurch."

Prime Minister John Key said after a February earthquake that killed 181 people that up to 10,000 homes in New Zealand's second largest city would have to be demolished and entire suburbs abandoned.

There has been pressure from residents for further details since a 6.0 tremor on June 13 caused further damage, including liquefaction, which occurs when tremors break the bonds between soil particles, creating a quagmire.

Some home owners, such as Simon Bourke, have said they want to leave the city but are still paying mortgages on ruined properties and cannot move until their fate is known and insurance payouts settled.

"I just want to get out... (but) if you move away you chuck away your whole financial future," he told AFP after last week's quake again surrounded his home with huge mounds of silt.

Key, who will be in Christchurch for Thursday's announcement, said this week that the bill from three major earthquakes in the past nine months had soared to NZ$25 billion (US$20 billion), far more than previously thought.

He said the city had endured about 7,500 aftershocks of magnitude 3.0 or above since the first quake on September 4 last year.

Brownlee said the announcement would not provide all the answers for residents but should give them some certainty about the future.

A 5.1-magnitude tremor late Tuesday briefly cut power to 11,000 homes and forced the city airport to close while engineers inspected its runways.

By noon on Wednesday (0000 GMT), New Zealand's GeoNet monitoring service reported another 17 aftershocks in the city.

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