NRS EMBANKMENT CO-SEISMIC DEFORMATION CALCULATIONS B4. PURPOSE Estimate the potential co-seismic deviatoric (shear) embankment deformations under earthquake loading for the NRS stockpile embankment. B5. OBJECTIVES 1. Select design response spectra and mean moment magnitudes (Mw) for the stockpile site (Vs30 = 600m/s) for an: a. 150 year return period event b. 2,500 year return period event 2. Estimate the co-seismic deviatoric deformations induced by earthquake shaking using the Bray and Macedo (2019) calculation method. B6. DESIGN RESPONSE SPECTRA A seismic hazard study was undertaken by GNS Science in 2017 (Ref. 1) for the Waihi Operation site with a time average shear wave velocity over 30m, Vs30 = 600 m/s, representative of a soft rock site. The GNS study provided probabilistic uniform hazard spectra for the required: • 150 year return period earthquake event • 2,500 year return period earthquake event 6.1. 150 year return period earthquake event The 150 year return period uniform hazard spectrum is shown in Figure B2 and the associated deaggregation plots are shown in Figure B3, Figure B4 and Figure B5 for PGA, SA(0.5s) and SA(1.0s), respectively. The mean magnitude of the deaggregated earthquake sources for PGA (Peak Ground Acceleration) is provided by GNS (Ref. 1), however, not for SA(0.5s) and SA(1.0s). These have been visually estimated as summarised in Table B9 by EGL for use in estimating co-seismic displacement.
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