CHRISTCHURCH, New Zealand—The magnitude 7.1 earthquake that hit Christchurch on New Zealand’s South Island could result in insured losses between $1 billion and $4.5 billion according to catastrophe modeling companies AIR Worldwide Corp. and EQECAT Inc.

Boston-based AIR said losses likely would be in the range of $2 billion to $4.5 billion, while Oakland, Calif.-based EQECAT said early estimates suggested a potential insured loss of $1 billion to $4 billion.

The earthquake hit Saturday along a previously unknown fault line, according to the New Zealand Institute of Geological and Nuclear Sciences, causing damage in Christchurch’s business district and 15 miles away. Several aftershocks also were reported.

There were no fatalities.

Losses are likely to fall largely in the reinsurance market, sources said.

Mike Pereira, team leader of Aon Benfield’s Asia Pacific division in London, said it was still too early to tell the extent of losses.

Aon Benfield is the reinsurance broker for the country’s Earthquake Commission, which covers all personal lines customers with home and contents insurance. Policyholders have three months after an earthquake to file claims.

New Zealand is a heavily reinsured market, and much of that coverage is placed in the global markets, Mr. Pereira noted.

Sydney-based Insurance Australia Group Ltd., which has a large presence in New Zealand, said in a statement that it was too early to assess the full extent of the damage caused by the earthquake but that it expected claims from the event to be covered by reinsurance.