The Royal Commission into the Canterbury Earthquakes has been told developers should be required to submit soil reports before building on land prone to liquefaction.
Liquefaction, where sandy soil turns to liquid, is the main reason so many Christchurch buildings have to be demolished.
University of California geotechnical expert Jonathan Bray told the commission that developers in the United States had long opposed the requirement to submit soil reports, because of the cost.
Dr Bray says it took the 1989 San Francisco earthquake to push state legislators into making it mandatory.
