Understanding Seismic Hazard in Aotearoa New Zealand’s Low Seismic Region

There are large swathes of Aotearoa New Zealand lie away from the Australian-Pacific plate-bounding faults, but where large damaging earthquakes can still occur. Accurately characterising earthquakes hazard in these “low seismicity regions” remains a key challenge as: (1) there is less data to constrain when and where future earthquakes will occur, and (2) the lack of felt earthquakes means that awareness to seismic risk in these regions is often relatively low. It is in this context that I undertook a multidisciplinary research program into the seismic hazard of the low seismicity southern South Island. Key outcomes of this research are: (1) new constraints on a ‘reservoir’ of earthquake prone crust at depths 15-35 km below Southland, (2) justification of changes to the statistical model used to forecast earthquake rates in Otago in the 2022 National Seismic Hazard Model update, and (3) advances to our understanding of where prehistoric earthquakes have occurred, and will likely do so again in future, in Southland. These results will be of use in future national and regional-level earthquake hazard assessments and should motivate the collection of more data to constrain seismic hazard in Aotearoa New Zealand’s other low seismicity regions.

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