University of Otago researchers have used kelp genetics and new data from laser mapping to identify a new area of the Marlborough coast which lifted up out of the sea during an ancient earthquake.
Co-author and Otago zoologist Prof Jon Waters said the area in Rarangi had been "hiding in plain sight" all along.
"In a geologically well studied country like New Zealand, there is still a lot to learn about our history of earthquakes and changing landforms," he said.
The study gave new insights into the changes in New Zealand’s landscapes and the recent history of earthquake impacts.
It used lidar mapping (remote sensing technology used to model ground elevation) and genetic analysis of bull kelp from the uplifted section of coast.
He said researchers identified a previously unrecognised area of uplifted rocky coastline — a bench about 1m above sea level — and a genetic anomaly in kelp below that bench.
The researchers believed the earthquake responsible, occurred about 2000 to 3000 years ago, showing the potential for kelp to record geological disturbance events.
"The area is close to a well-known active fault and several big past earthquakes have been well quantified by other researchers, but this coastal uplift zone was not previously known.
"The evidence for it is extremely clear now we’ve had a chance to look more closely.
"Rarangi is also a very popular summer swimming spot, rather than some obscure or remote location, and the evidence of coastal uplift was hiding in plain sight."
Prof Waters said the research was the latest output from the group’s Marsden-funded project which assessed earthquake impacts on coastal species.
"This work serves to highlight again just how dynamic our country is — and how earthquake uplift leaves long-lasting signatures in our coastal species."
