"Physical damage like rock fall or cracked/broken stalagmites and stalactites as well as chemical changes inside stalagmites."
Stalagmites and stalactites are mineral deposits that slowly build up over time as water drops from the ceiling of a cave.
Stalagmites are formations on the grounds of caves whereas stalactites are the formation on the ceiling of caves.
It is believed dating stalagmites and stalactites could be more accurate than other landforms.
Current methods include raised beaches, sunken shorelines, offset river courses, fault scarps and landslide deposits.
"This new method could extend the existing earthquake record by tens or hundreds of thousands of years as cave deposits are relatively protected from surface erosion and stay preserved for much longer."
Large Hikurangi subduction earthquakes are thought to happen very infrequently, around one every 800-1000 years.
The three-year project is lead by the University of Auckland alongside Victoria University of Wellington, University of Waikato, GNS Science, University of Melbourne (Australia) and Centre for Star and Planet Formation (Copenhagen).
It is part of a larger project on stalagmites and stalactites, looking at volcanic super-eruptions and the impacts of volcanism on local and global climate, as well as earthquakes.
The Hikurangi subduction zone is a faultline that runs up the East Coast, and is New Zealand's largest faultline.
The 1931 Napier earthquake was not a subduction zone earthquake.
