A time-dependent seismic hazard model following the Kaikōura M7.8 earthquake

ABSTRACT

Following the 2016 M7.8 Kaikōura earthquake, a time-varying seismic hazard model (KSHM) was developed to inform decision-making for the reinstatement of road and rail networks in the northern South Island. The source model is the sum of a gridded 100-year earthquake clustering model and an updated fault source model. The gridded model comprises long-term, medium-term and short-term components. The 100-year gridded model is constructed as the sum of 100 annual forecasts. A discounting method trades off expected earthquake occurrences of the distant future against those of the near future. The fault source model includes updates to account for newly revealed faults that ruptured in the Kaikōura earthquake and other recently obtained new information, and new time-varying probabilities of rupture for four fault segments. Two different characterisations of the Hikurangi subduction interface are incorporated via a logic tree, with weights determined by an expert panel. A suite of ground motion prediction equations contribute to a logic tree in order to account for epistemic uncertainties in source modelling for each of four tectonic region types. Here, we compare the resulting hazard estimates with the 2010 National Seismic hazard Model and recorded motions in past New Zealand and global earthquakes.

KEYWORDS:

• Seismic hazard
• time-dependence
• aftershocks
• clustering
• PSHA
• Kaikōura earthquake

Acknowledgements

We acknowledge the New Zealand GeoNet project and its sponsors EQC, GNS Science, LINZ, NEMA and MBIE for providing the earthquake catalogue data used in this study. Some of the research was undertaken for the North Canterbury Transport Infrastructure Recovery (NCTIR). The GNS Science Hazard and Risk Management Programme supported the preparation of the manuscript.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Data availability statement

The earthquake catalogue data that support the findings of this study are available from the GeoNet website at https://quakesearch.geonet.org.nz/. The fault source parameters data supporting the findings of this study are available within the article and its supplementary materials.

• Supplement 1 is available at Zenodo: https://zenodo.org/record/7340153#.Y45vx9JByXJ.

• Supplements 2–4 are available at the GNS Science Dataset Catalogue:

• Supplement 2, https://doi.org/10.21420/VRYT-VT95;

• Supplement 3, https://doi.org/10.21420/Y8HV-GX02; and,

• Supplement 4, https://doi.org/10.21420/83FE-H882.

Fault source locations are available on request.