Scientists move a step closer to understanding earthquake hazard

Improvements to a new seismic hazard model should make estimating the likelihood of future earthquakes and shaking in New Zealand easier, reports the latest Natural Hazards Update, published today from the Natural Hazards Centre.

6 August 2003

The national seismic hazard model is based on combining the 160-year historical record of earthquakes with prehistoric earthquake information from over 300 active faults in New Zealand. This new approach therefore combines prehistorical and historical information to estimate how often earthquakes are produced around a site, as well as the traditional focus on where the largest earthquakes are.

The Institute of Geological & Nuclear Sciences (GNS) is leading a collaborative effort with NIWA to update the active fault database used in the seismic hazard model. ‘Currently, the model is limited to information from onshore fault sources throughout New Zealand,’ says GNS Hazard Modeller Mark Stirling. ‘NIWA will provide information on faults from offshore coastal and continental shelf areas; in particular, active faulting zones from offshore Canterbury, Hawke Bay, Fiordland, Manawatu, Cook Strait, and Bay of Plenty.

‘With GNS and NIWA joining forces to link the onshore and offshore marine faulting, it will be possible to produce a much better model of the seismic hazard for New Zealand,’ says Dr Stirling. ‘This research is part of a bigger effort to update, improve, and validate the seismic hazard model. The Earthquake Commission (EQC) and United States agencies are also contributing to our development of tests for models such as this.

‘All these improvements will greatly increase the reliability of the national seismic hazard model, enabling us to provide a more soundly-based appraisal of the seismic hazard for different regions in New Zealand,’ says Dr Stirling.

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