Tauranga Hospital has four earthquake-prone buildings, including the theatre block and main ward, the district health board has revealed.
An earthquake-prone building is more likely to be damaged after a moderate earthquake and so would be a higher risk to public and staff safety.
Tauranga is a medium-risk zone for earthquakes compared to other parts of the country such as Wellington, which is categorised as high-risk.
The four buildings at Tauranga Hospital classed as earthquake-prone are the kitchen and site-wide building services in the building's basement (T20), offices and support services building and transit lounge (T24), main ward and clinical services block (T45) and the theatre block (T46).
To bring the kitchen and building services up to code, the building would have to be demolished and the basement walls strengthened. But the long-term plan is that the building will be replaced by a proposed new Clinical Services Building;
Strengthening work has already been done on the exterior of the offices and support services building and transit lounge building but more work would be needed to upgrade the internal walls. The building would need to be vacated before the work could start.
To bring the main ward and clinical services block and the theatre block buildings up to code, the primary structure, floor and foundations would need strengthening, but the health board already hopes to build a new Clinical Services Building.
The repair work must be done in the next 12 and a half years.
Hutt Hospital's Heretaunga Ward block was vacated because of seismic issues last month and other health boards have been asked about their seismic assessments in the past few days, Bay of Plenty District Health Board said.
"[We] also need to do further seismic upgrading at Tauranga Hospital to achieve the latest standards.
"We have received expert engineering advice that the risk to people while we plan the future for the buildings is low.
"The safety of our staff and patients is our priority, as is maintaining our hospital's clinical and acute services."
An earthquake-prone building doesn't need to be empty and there were a number of differences between Tauranga and Hutt hospitals, the board said.
Hutt Hospital is on the main Wellington faultline in a much higher earthquake-risk zone and its seismic rating is extremely low.
Tauranga Hospital can either upgrade over 12 and a half years or build a new Clinical Services Block and vacate the earthquake-prone buildings.
Whakatāne Hospital is not earthquake prone.
The health board says it is "proactively" monitoring and managing the risks associated with Tauranga's buildings.
"We are developing a business case to build a new Clinical Services Block, which can bring the hospital up to latest standards and address our accommodation pressures for the longer term.
"The business case will also consider a greenfield build option if suitable land is available."