GNS Science Conduct Trench Work On Rauoterangi Fault

GNS Science has conducted a geotechnical study on the Rauoterangi Fault in Feilding in the hope to carbon date the fault line and analyse the risk it poses.

The study has been fully funded by the Earthquake Commission Kōmihana Rūwhenua (EQC), with Manawatū District Council covering some remedial costs. A trench was dug in an area of Rimu Park that has been identified as having surface deformation caused by the fault line.

“Fault trenching provides another means of ground-truthing the work we do. We expect to see some evidence of past fault movements on the trench walls and we’ll also hope to use radiocarbon dating to get a date on any past ruptures,” says Dr Robert Langridge of GNS Science.

The reclassification of the Rauoterangi Fault was announced on Tuesday 9 February by Manawatū District Council, when a GNS Science report was made publicly available to the community. Property owners who were identified as being in a Fault Avoidance Zone (FAZ) received letters from Mayor Helen Worboys advising them of the new information in the report and what this meant for them.

Council was successful in applying for funding from EQC to contract GNS Science to do the trenching work, which Langridge believes will provide more information for residents and the wider community that will be beneficial for future land use and development.

“The results of this work should give us a better handle on the activity of this fault. This information should give us all more confidence about the hazard that the fault poses. After all, there is a hazard there, this work just aims to better characterise it.”

EQC’s Research Manager Dr Natalie Balfour says EQC is very happy to support the Council in their efforts to find out more about the fault.

“Results from the trenching of the Rauoterangi Fault should give the Council and community more detailed information to help make decisions about how to reduce impact from a future earthquake. Knowing more about how the fault behaves, and how often it has ruptured in the past will be very useful for preparing for the future.”

The work at Rimu Park took five days and the carbon dating results of the Rauoterangi Fault are expected to be known in four months’ time.

Rauoterangi Fault Trench Survey video
 

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