Ancient earthquake’s impact uncovered by researchers.

By combining the scientific forces of genetics and geology, University of Otago researchers have identified a new region of coastal highlands, which has been hiding in plain sight.

The previously unknown region of earthquake height, in Rarangi, Marlborough, was discovered using a combination of new data from laser mapping and kelp genetics.

Co-author Professor John Waters, from the Department of Zoology, says the study gives new insights into changes to the landscape of Aotearoa and the recent history of earthquake impacts.

“In a country as geologically well-studied as New Zealand, there is still a lot to learn about our history of earthquakes and changing landforms,” ​​he says.

The paper just published in Facade Journal of the Royal SocietyLiDAR maps (a remote sensing technique used to model land elevation) and genetic analysis of kelp from the elevated section of the coast were used.

The team identified a previously unrecognized region of rocky, upland coastline — a bench about 1 meter above sea level — and a genetic anomaly in kelp below that bench. The kelp’s genes indicate that the species became extinct in the area after the earthquake, before being recolonized by kelp that drifted from 300 km south.

The group believes the responsible earthquake occurred around 2,000 to 3,000 years ago, which indicates the possibility that kelp recorded geological disturbance events.

“The area is close to a known active fault, many previous large earthquakes have been well measured by other researchers, but this coastal uplift area was not known before – the evidence for it is so clear now that we have a chance to look more closely.”

“Raranji is also a very popular summer swimming spot, and it is not a place that is obscure or remote, and evidence of coastal uplift was hiding in plain sight,” says Professor Waters.

The research is the latest output from a project funded by the group’s Marsden to assess the effects of the earthquake on coastal species.

“Our work uses a combination of genetics and geology, and it is very exciting that these combined methods have allowed us to locate a previously unknown coastal uplift in New Zealand.

“This work serves to highlight once again how dynamic our country is – and how seismic uplift leaves long-lasting imprints on our coastal species.”