Civil Defence local controller Paul Cooper said they were inspecting core facilities but no damage had yet been located.
"We are encouraging building owners to get their buildings checked, particularly if they are deemed earthquake prone.
"Remember, just because a building is new does not automatically mean that it isn’t earthquake prone," Mr Cooper said.
Timaru Mayor Nigel Bowen said extra engineers had come down to help assess council facilities.
Stadiums and halls with bookings for this afternoon and those closer to the epicentre were being prioritised for rapid assessments.
Mr Bowen was sitting down when the earthquake struck.
"I sort of looked out the window for some major machinery but it had a good little rumble to it, only for about 10 seconds but yeah you certainly noticed it."
A seismologist earlier confirmed the strong earthquake, which happened at 9.14am at a depth of 10km, was not in the Alpine Fault.
It was the strongest earthquake to hit New Zealand this year.
It was described as a long, rumbling quake and didn’t cause any violent jolts.
GNS duty seismologist John Ristau told RNZ it happened almost exactly in the middle of the island but it's not clear yet which fault was triggered.
At this stage, the earthquake is believed to have happened at the junction of several fault lines, Mr Ristau said.
But he did confirm it occurred 100km east of the Alpine Fault line and is not expected to have any impact on it.
There were likely to be plenty of aftershocks, some as strong as magnitude 4.
Geraldine resident Fi McCafferty, who works for Geraldine News, said she was sitting at her desk in her villa when the earthquake struck.
"It was pretty shaky. It reminded me a lot of that first quake in Christchurch which we felt down here as well.
"The house felt like it was sitting on top of a big pile of jelly."
Nothing fell off the shelves at her place.
There appeared to be little damage in the town.
"Everyone is a bit on edge but the town appears unscathed."
A worker at Barkers of Geraldine said the day was continuing was normal and there was no damage of which she was aware.
ODT readers reported feeling the quake in Dunedin, Queenstown, Oamaru, Timaru and Christchurch.
There were more than 10,200 reports on Geonet of people feeling it. the majority across the South Island and some in North Island.
Andy Somerton, owner of the Fairlie Bakehouse told the New Zealand Herald he felt at least thirty seconds of shaking and considered diving under furniture.
"We were making that call in our mind, whether we needed to get down or not," he said.
"We felt it and our first thought was ‘ah, please tell me that’s not Christchurch again."
The shaking was “really strong", the bakehouse owner said and he feared damage had been done to his store.
A quick inspection showed his shop was fine.
Earlier in the year Canterbury was rocked by earthquakes measuring between 4.4 and 4.7. The quakes, in March and April, were the largest in the region in 2023 before today’s event.
- Additional reporting NZ Herald
