Geonet updates quake risk

Latest earthquake forecasts show there is a 2 per cent to 14 per cent or “very unlikely” chance of a large earthquake occurring in central New Zealand over the next year, but an increased chance of a large event in the next decade.

Geonet has released 1-year and 10-year earthquake forecasts, using a new modelling system looking at how slow slip events might impact future shakes.

Evidence of earthquake clustering over the past few thousand years was used to revise the likelihood of large events.

GNS Science seismologist Dr Matt Gerstenberger said the forecasting showed the likelihood of a magnitude 7 or higher earth in the next year in the central North Island was “very unlikely” — with a 2-14 per cent chance.

The best estimate was 6 per cent, which was a one-in-16 chance. While this was lower than at this time last year — following the 2016 Kaikoura earthquake the probability was greater than 20 per cent — it was up on previous years.

“So that’s increased from what we would have said prior to the Kaikoura event. And it’s already quite a high probability area,” Gerstenberger said.

GNS scientists met with Asian and US experts to create these estimates, which Gerstenberger said added to their own knowledge.

The team also created an estimate of how likely a large earthquake was within the next 10 years. The best estimate of a large-scale earthquake happening in central New Zealand in this time period was 30 per cent.