Overview
- University of Auckland researchers used trenching, ground‑penetrating radar and radiocarbon dating to show the Mangatangi Fault alongside the Hunua Ranges moved in the past roughly 10,000 years, meeting New Zealand’s definition of an active fault.
- The team’s models indicate a full rupture of the fault could produce about a magnitude 6.8 earthquake, which the authors say would have serious consequences for people in South Auckland and could affect parts of central Auckland.
- Lead authors stress the result is a long‑term finding, not a short‑term warning, and say the fault may not rupture again for tens of thousands of years, leaving the immediate probability uncertain.
- The discovery renews questions about Auckland’s current low seismic‑hazard classification and the 2025–26 government exemption from some earthquake‑prone building rules, because an upgraded hazard rating would trigger tougher building requirements.
- Researchers, funded in part by the Natural Hazards Commission, are expanding mapping and dating of Auckland‑area faults to refine hazard estimates as the region’s southwest growth brings more people and infrastructure closer to the fault.