Auckland and Northland hospitals have had to temporarily quake-proof their data centres after a warning they were not up to scratch.
Meanwhile, Christchurch Hospital has not properly assessed its data centre, which is in an earthquake-prone building, even though damage to them could jeopardise vital medical services.
Documents released under the Official Information Act show hospitals' response to earthquake risks is slow, seven years on from the Christchurch quake.
Data centres enable the likes of operating theatres and MRI scanners to work.
But the northern region hospitals - run by the Auckland, Counties Manukau, Waitematā and Northland district health boards - had the two data centres they share, with 63 racks of computer servers across 200 square metres, assessed only last year.
"There was a lack of seismic restraint and hold down to most of the equipment within the room. Items are simply sitting on... the floor," the audit by engineering consultants Aurecon said.
"There are cases where the equipment has wheels which do not appear to be stabilised or locked to prevent movement during a significant earthquake.
"The cables are connected directly through the raised floor tiles and during an earthquake it is likely the cables will be shorn."
Since the audit, some basic seismic restraining had been done and the centres made safer for anyone working in them, the Auckland DHB said in its OIA response to RNZ.
The hospitals are now shifting most of the data services to Government-approved data centres elsewhere over the next three years.
"This strategy will further reduce risk from the hospital data centres," chief executive Ailsa Claire said.
In Japan and California, quake-proofing of data centres can include base isolators on the entire floor so they do not move as a building sways.
Wellington Hospital has put its 16 racks of servers on base isolators.
Christchurch hospital, however, has its 12 server racks bolted to the floor in its earthquake-prone Parkside building.
"The earthquake prone classification for Parkside relates to the cladding on the outside... not the building's overall structural integrity. For that reason there is no need to move the data centre," the DHB's planning director Carolyn Gullery said.
The Parkside was rated about half as strong as a new building before the 2011 quake and suffered "modest" damage in that one.
A back-up data centre would operate out of the new Acute Services block once it opened late next year, Ms Gullery said.
However, the health board - which previously told RNZ it had commissioned 24,000 reports about its buildings post-quake - has not assessed the seismic restraints in its data centre.
"We have undertaken more general reviews of all facilities to help ensure there are no life safety issues. Seismic restraints form part of those general reviews."
The Insurance Council has been pointing out that the standards are widely ignored in New Zealand buildings. It said for assessment to be worthwhile it must be done by engineers familiar with specific standards.
Other documents released under the OIA by the Ministry of Health show the country's hospitals have about 110 earthquake-prone buildings, with that number slowly creeping up, despite this number not including buildings at Middlemore which are still being assessed.
Six of these hospital buildings contain patient services and are in the most critical importance category.
DHBs that have done seismic reviews and embarked on long-term upgrades (as at January 2018): Auckland, Tairāwhiti, Lakes, Mid-Central, Nelson-Marlborough
DHBs that have seismic reviews underway: Counties Manukau, Hutt Valley, Capital and Coast, Bay of Plenty (limited).
DHBs about to engage with consultants over seismic reviews: Waitematā, Taranaki, Wairarapa, Waikato.
DHBs only doing seismic reviews when they refurbish: Southern, Whanganui.
DHBs which did not provide information about non-structural seismic work to Ministry by Jan 2018: Northland, Canterbury, West Coast, South Canterbury.