Site-specific seismic hazard analysis - evolving developments in practice

Abstract

Site-specific hazard analyses (SSHAs) are undertaken to inform seismic actions for the design of important projects in New Zealand. These have typically adopted the 2010 National Seismic Hazard Model (NSHM) as the reference NZ Source Model.

Advances in SSHA practice have included the adoption of modern NZ-region specific and international ground motion models, with epistemic uncertainty considered using logic trees. Where appropriate, modifications to the 2010 NSHM have also been made, informed by recently published paleo-seismological studies on major fault sources. Other considerations have included making the SSHA truly ‘site specific’ by assessing local effects due to fault proximity, basin edge, topographic, and soft soil response.

This paper presents a review of selected SSHA for sites in NZ and the South Pacific, including efforts to incorporate ‘site-specific’ aspects into the assessment, and consider both seismic hazard and engineering design aspects in the development of recommendations for seismic design actions for engineering projects. The discussion includes thoughts on application of 2022 NSHM hazard results in developing recommendations for future projects.