A boy who lay dead in a hospital morgue that collapsed when the 1931 Hawke's Bay earthquake struck was mistakenly included in the death toll, new research has found.

The first wide-ranging study into the casualties of the 7.8 magnitude earthquake also reaffirmed the number of deaths at 256 - debunking a 2016 Ancestry.com investigation which concluded that 253 people had died.

Only one substantially intact body, of an elderly woman was never identified or linked to a named person.

The latest study, conducted by a team of epidemiologists, disaster experts, a genealogist and an engineer, along with academics from three New Zealand universities (Otago, Massey and Auckland), focused on the death certificates for anyone who might have died in the quake.

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Senior author, Professor Nick Wilson from the University of Otago, Wellington, said the key difference in their analysis was that they included people who had been severely injured in the earthquake, but died several years later due to those injuries.

Lead researcher Christine Clement said this process resulted in them adding 17 people to previous lists of earthquake victims, but removing 14 people.

Hawke's Bay historian, Michael Fowler said such a massive switch up was entirely possible, as there was "such chaos and movements of people around and records destroyed by fire".

Furthermore, the study found that the 256 deaths and more than 600 serious injuries, in a population believed to be about 50,000 were in part caused by a lack of adequate regulations for building construction in large CBD buildings.

Just 3 per cent of the deaths occurred in people's homes, almost all of which were at that time constructed from wood.

Sailors beside collapsed building on the corner of Dalton and Tennyson Streets, Napier. Photo / Knowledge Bank
Sailors beside collapsed building on the corner of Dalton and Tennyson Streets, Napier. Photo / Knowledge Bank

Instead, it was the collapse of just 15 buildings which resulted in 58 per cent of fatalities.

Wilson said many of the buildings which collapsed were multi-storey constructions made of unreinforced masonry, which were not only a danger to those inside but also killed people in the street.

These deaths in the street accounted for 19 per cent of all earthquake deaths.

"The picture for this 1931 earthquake had some similarities to the Canterbury earthquake of 2011 in that specific buildings caused most of the deaths and unreinforced masonry fell into streets, killing people there."

Wilson says the value of wooden buildings had repeatedly been shown in earthquakes in New Zealand, going back as far as the 1848 Marlborough earthquake.

However, the lessons of this and further earthquakes were not put into building regulations and New Zealanders continued building in insufficiently reinforced brick, including in multi-storey buildings.

"This was partly understandable when considering the higher fire risk in earlier times, but there seems to be no good excuse for New Zealand authorities to continue to have allowed unreinforced chimneys and masonry on buildings above busy streets in a country with regular earthquakes."

He said the multiple benefits of building with wood are increasingly being recognised with multi-storey wood buildings now being built around the world.