Government agencies twice failed to act on calls for more research that could have helped Christchurch prepare better for February's fatal earthquake, victims' families have claimed.
The families say the agencies "didn't do the right things" and missed several chances to identify high-risk areas and strengthen key buildings.
They say the first opportunity was missed in 2005, when consultants Opus urged Environment Canterbury to model a magnitude 7 earthquake "on a hidden earthquake source close - say 10km to 20km - to Christchurch".
February's earthquake was a magnitude 6.3 tremor on a buried fault around 9km from the city centre.
Environment Canterbury's director of investigations and monitoring, Ken Taylor, said most of the Opus recommendations were taken up by Crown research institutes GNS and Niwa in a project called Riskscape.
Riskscape models the danger posed by earthquakes, tsunamis and other hazards across the country, but is not yet complete.
Jim Cousins, a GNS scientist who has worked on Christchurch earthquake modelling, said he did not think the Opus recommendation had been carried out. "If it had been done, I would have probably known about it."
In response to an Official Information Act request, Environment Canterbury indicated it had commissioned further research on hidden faults in 2008, but was unable to explain what use it had made of it.
The agency said it "has tested the prototype Riskscape model, but has not used it to run risk assessments".
Rachael Ford, whose uncle died in the February 22 quake, said the agencies' response was inadequate.
"This research should have been done," she said. "And if it had been, I think there would have been a far better mindset around preparation."
However, Mr Cousins said even if the modelling had been carried out, a major earthquake might still have been regarded as unlikely and not planned for.
"It would have suffered the same difficulty as other modelling - it would have been given a very low probability."
Ms Ford also claimed authorities missed a second chance to prepare for February's earthquake, which killed 181 people.
After the September 2010 earthquake, GNS applied to the Canterbury Earthquake Recovery Commission (Cerc) for funding to carry out a study of hidden faults under Christchurch.
At the time a leading geologist, Geotech Consulting's Dr Mark Yetton, told a Christchurch newspaper that money spent on "good quality, modern seismic surveys" had been needed "for quite a while".
However, Cerc was wound up and replaced by the Canterbury Earthquake Recovery Authority before it had a chance to process funding applications. GNS' resubmitted application was approved only after February's earthquake.
Ms Ford said it showed agencies "just haven't done the right things".
"What they should have done, and what's been done in other cities that have suffered earthquakes, is have the blind faults studied."
GNS scientist Kelvin Berryman said the application had suffered "a bit of bureaucratic hurdles and go-slow", though it had been "expedited quite quickly" after February's earthquake.
However, even if approved immediately, the research might not have been completed before February, and would only have been indicative, he added. "We weren't going to stop an earthquake happening even by finding out there were faults there."
Ms Ford also claimed authorities had failed to create a detailed earthquake risk map of Christchurch, as was done in parts of California following a major earthquake in 1971. Such a map might have revealed that buildings in certain areas needed further strengthening or other action, she said.
Mr Berryman said that despite February's earthquake, Christchurch was an area of low seismic activity. Limited resources meant detailed mapping had inevitably been concentrated on areas of greater risk, such as Wellington, he said.