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The 2022 Revision of National Seismic Hazard Model (NSHM) for New Zealand: Candidate Ground-Motion Models (GMMs) and Associated Hazard Sensitivities

Description: 

For the 2022 revision of the national seismic hazard model (NSHM-2022), the ground-motion characterization modeling (GMCM) adopts a hybrid approach (to capture epistemic uncertainty) that involves using a multimodel and backbone ground-motion modeling framework. For active shallow crustal sources seven GMMs were considered that include four global, one New Zealand specific GMM and two New Zealand specific backbone GMMs developed within the purview of NSHM-2022. Similarly, the candidate models for subduction (interface/intraslab) sources include three recently developed global GMMs (NGA-Sub) and one New Zealand specific backbone model.

The candidate GMMs were assessed primarily by performing comparisons of median ground-motions and aleatory uncertainty owing to the limited data in the magnitude and distance range that dominate hazard in the country. Nevertheless, data driven evaluations were also carried out using the global datasets in addition to the recently compiled strong motion database for New Zealand. Moreover, for subduction GMMs, corrections were also made in the median models for backarc distance scaling and in the aleatory sigma model for soil non-linear effects. We demonstrate the impact of updated GMCM on the hazard calculations: 1) by showing comparisons with respect to 2010-GMCM and 2) relative sensitivity of different GMMs and parameter choices corresponding to different source types. Final weights on different models were decided after an expert elicitation workshop.

Session: Advances in Probabilistic Seismic Hazard Analysis and Applications

Type: Oral

Date: 4/19/2023

Presentation Time: 10:30 AM (local time)

Presenting Author: Sanjay Bora

Student Presenter: No

Invited Presentation: 

Authors