EGL Ref: 8983 8 October 2021 Page 10 File: TSF3 Stability Analysis Appendix Summary.docx.doc TABLE B8: ESTIMATED MEAN MAGNITUDES FOR 150 YEAR RETURN PERIOD SPECTRAL ACCELERATIONS Intensity Parameter Mean Magnitude (Mw) PGA 6.3 SA(0.5s) 6.4* SA(1.0s) 6.7* *Visually estimated from GNS 2017 deaggregation 6.2. Safety Evaluation Earthquake - Kerepehi Fault System earthquake event and aftershock The deterministic response spectrum for a rupture on the full (onshore) Kerepehi Fault System is shown in Figure B5 as one of the two cases considered under the Safety Evaluation Earthquake criteria. The spectrum shown is for a magnitude 7.3 rupture, for shaking one standard deviation (i.e. 84%ile or epsilon value equal to one)) above the median estimate using McVerry et al. (2006) (Ref. 2) and Bradley (2013) (Ref. 3) ground motion prediction equations. An aftershock of one magnitude less is to be considered with the main rupture for the Safety Evaluation Earthquake when assessing effects. The aftershock spectrum is assessed using the same ground motion prediction equations as for the main rupture, for shaking intensities one standard deviation (epsilon value equal to one) above the median predicted. Table B9 summarises the magnitudes. The Kerepehi Fault System is 21km from the Waihi Operation. FIGURE B5: SEE KEREPEHI FAULT SYSTEM RUPTURE (84%ILE MOTION) RESPONSE SPECTRA TABLE B9: ESTIMATED MAGNITUDES FOR THE KEREPEHI FAULT SYSTEM RUPTURE Rupture Event Magnitude (Mw) Main rupture 7.3 Aftershock 6.3* * Taken as one magnitude less than the main rupture
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