Research provides guidance around recurrence for parts of the Rauoterangi Fault
Research has helped better define the chance of a significant earthquake along part of the Rauoterangi Fault.
The Manawatū District Council sought funding from the Toka Tū Ake EQC last year to contract GNS Science for further surveying of the district’s fault lines last year after several were reclassified as active – one being the Rauoterangi Fault, which passes through Feilding.
Paleoseismic trenching was carried out by GNS Science earthquake geologist Dr Rob Langridge and his team to understand the surface rupture history of the eastern strand of the Rauoterangi Fault in Feilding. Their results show there have been two ruptures of this strand in the last 30,000 years or so.
While the chance of a significant earthquake has always been there for Feilding, Toka Tū Ake EQC Manager Research, Dr Natalie Balfour says understanding the recurrence intervals can help communities plan and prepare.
“It was important to understand the hazard as the fault runs under homes, businesses and even a school. We’re hopeful this research will help those who have key roles in regional planning and emergency management to understand and manage potential seismic hazards in the area,” Dr Balfour says.
Recurrence intervals are used as a guide around fault activity – the shorter the recurrence, the more likely for future earthquakes. It is estimated the recurrence interval of the eastern strand of the Rauoterangi Fault is between 10,000-20,000 years, rather than 5000 to 10,000 as previously thought.
These results will assist council with future planning across the local community, ensuring new buildings – including medical and post-disaster facilities, and schools – aren’t built within fault avoidance zones.
“Our goal was to provide some certainty for Manawatū District Council, who have proactively championed this work in Feilding,” Dr Langridge says. “We have been able to recommend changing the recurrence interval class for the eastern strand from RI Class IV to V, which is a good outcome for the town and the local school.”
“We appreciate that the Rauoterangi Fault is a low activity, long recurrence section but the main shaking hazard in Feilding still results from the Wellington and Mohaka faults, as well as the Hikurangi subduction zone, which all have much shorter recurrence times and the possibility for larger magnitudes,” Dr Langridge adds.
With that said, Dr Langridge encourages those living in the district to follow the preparedness advice of Manawatū District Council, Toka Tū Ake EQC and local Civil Defence.
You can find information about how to get prepared at:
“Looking at what has happened in the past gives us the opportunity to think through how we might deal with a similar event in the future. The fact is, no matter where you live in Aotearoa, we all need to be prepared for natural hazards,” Dr Balfour adds.
The final report can be found on the Manawatū District Council website: http://www.mdc.govt.nz/gnsreport