Another earthquake in Christchurch could prove the most costly yet, with the city's insurance policies expiring on Thursday and no commercial insurers willing to touch Canterbury.

The Waimakariri and Christchurch councils have been told they won't get new earthquake cover, leaving the councils - or the Government - having to pay if assets such as AMI Stadium, the Town Hall, the convention centre, all council buildings and even underground infrastructure are further damaged.

Councils have been forced to go cap-in-hand to the Government.

In Christchurch's case, the above-ground assets it owns are worth $1.85 billion.

Councils insure a lot of their assets with a Local Government New Zealand-owned company, Civic Assurance.

Policies for both underground and above-ground assets expire around the country on June 30 and Civic Assurance chief executive Tim Sole has confirmed they will not be renewed in the south.

"We cannot insure because we don't have reinsurance," he said.

The company's capital base of $20 million had been reduced to just over $10 million because of the three big Canterbury earthquakes. Each earthquake had cost it $3.6 million.

The rest had been covered by its reinsurance, a bill that now came to $600 million.

There had been fears international reinsurers may baulk at any New Zealand local body reinsurance, but an industry insider said it was "more than likely everyone outside Canterbury will be able to find cover with Civic or someone else". It was a "pretty serious" situation.

Christchurch City Council's general manager corporate services, Paul Anderson, said the council was not sure what it would do. "We're working with our brokers to continue to try and place insurance. It's a huge battle."

It wasn't sure at this stage whether it would be able to get insurance even if earthquake cover was excluded.

Waimakariri District Council wrote to the Government about the issue on Friday. Manager of finance and business support, Jeff Millward, said: "Our brokers have said we're 99.9 per cent sure to get insurance, but not for earthquakes."

That included anything to do with earthquakes, such as fire, tsunamis and volcanic eruptions.

"Therefore we have no option but to put a proposal to the Government and ask for some sort of cover until confidence is restored back into the market.

"At the end of the day, what do you do?"

There were several more quakes yesterday, the biggest of magnitude 4.2.