Heavily populated south Dunedin could be sinking according to new research by the Institute of Geological and Nuclear Sciences.
The new data presented shows the ground beneath the low-lying sector of Dunedin has been steadily sinking for the past 20 years.
Geologist David Barnell says the rate is small but over a large amount of time, significant.
"The ground is going down at an average rate of around 1mm per year, which over the space of a century would equate to 10cm."
Geologists now want to take their research further by using a scientific drill to analyse the bedrock in south Dunedin to see the extent of the subsidence.
Robert Smillie says the analysis will help them understand the area's geology better.
"From that, we can age-date the rocks and get some kind of idea about what historical rates of subsidence were occurring.
"Was there subsidence occurring over hundreds or thousands of years, and can we use that as a predictor for the future as well."
Dunedin City Council says it's yet to consider the report and how it affects south Dunedin - the Otago Regional Council says it's relevant in the long term issues surrounding sea level, where parts of the suburb are already close to sea level which was highlighted by last year's floods.
"It's consistent with the other trends that are showing that the difference between ground level and ground water level is reducing over time," Dr Gavin Palmer of the ORC said.