Golden Grove Mine PSHA

There was a significant reduction in the seismic hazard at this site for the 2500 return period in the published hazard map NSHA18 compared to the Hazard map published in 2013 by Geoscience Australia. The key reasons for the decrease in seismic hazard factors from 2012 to 2018 seismic hazard maps are due to:

• An increase in Gutenberg and Richter (1944) b-values, particularly in eastern Australia, resulted from the ML to MW conversions. This decreases the rates of rare large earthquakes relative to moderate-magnitude earthquakes.
• The use of modern ground-motion prediction equations (GMM) that do not rely on the PGV to PGA conversions. The recent GMMs also predict faster attenuation of PGA with distance and thus lower ground-motion hazard.
• A reduction in the rates of moderate-to-large earthquakes (MW ≥ 4.0); due to the correction of pre-1990 local magnitude ML estimates and the conversion of ML to M.
• To account for epistemic uncertainty, three seismic source models (with varying weightings) have been included in this assessment. The first model is the DIM-AUS (Dimas & Venkatesan, 2016) area source model. The second model is the AUS6 (Dimas & Gibson, 2016) area source model. The third model is the NSHM13 (Leonard et. al., 2012) model made of two layers, a main source zone layer and a background source zone layer. All the models are composed of a series of zones at shallow depths. The fault sources are included from Geoscience Australia’s Neotectonic Faults Database.