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\section{Probabilistic Seismic Hazard Analysis}  \subsection{Probabilistic Seismic Hazard overview}  Probabilistic Seismic Hazard Analyses (PSHA) (Cornell, 1968; McGuire, 1976), produce estimates of the probability of exceeding various levels of ground motion (intensity measures) for a given location and time interval. The primary aims are to produce seismic hazard curves—usually drawn with the annual rates of exceedance on the vertical and increasing values of intensity measure (e.g. values of PGA) on the horizontal. Alternatively, time intervals of interest are selected (e.g. 500 years) in which case a map of expected values of the intensity measure can be made.   The standard PSH methodology estimates hazard by summing the contributions from all potentially damaging earthquakes in the region, the primary steps are as follows, e.g. (Baker, 2008): 
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\item Characterize the source-site distance distribution.  \item Compute the ground motion (distribution) as a function of earthquake magnitude, distance; i.e. the conditional probability.  \item Combine all probabilities (and uncertainties) using the total probability theorem.   \end{enumerate} The application of traditional PSHA approaches requires estimation of the properties of the seismic source zones, which are often determined by subjective judgments that may be different in various studies. In low-seismicity areas such as Australia, the earthquake occurrence is often modelled as a spatio-temporal Poisson process, i.e. earthquakes are memoryless and spatially random, with rates that are completely described by the Gutenberg-Richter relationship (no ‘characteristic earthquakes’). The seismicity rates and frequency-magnitude distribution (b-values) are calculated from historical seismicity or from geologically derived fault slip rates (more commonly the former). The maximum credible earthquake (M_Max) is imposed given empirical deductions from past earthquakes and estimated maximum fault length. Given that SCRs tend to have highly clustered seismicity, it is common to subdivide the region into sub regions know as area source zones, in which it is supposed that the spatial-Poisson conditions are approximately valid.   In the last few decades, fault slip rates have increasingly been used to constrain earthquake recurrence relationships and inform hazard maps (Pace, 2006). In Australia, this technique has been incorporated into a couple of previous studies (Brown and Gibson 2004, Somerville et al. 2008). It is particularly useful in regions like Australia, however, where seismicity is relatively infrequent, historical records were likely derived from sparse networks and there are numerous geological features present that indicate recent seismic activity and that can be dated using a variety of techniques. Inclusion of fault sources represents a key point of difference between the current study and the latest national hazard map by Geoscience Australia.   Recently, PSHA has also come under criticism from a number of scientists (Klugel 2012; Stein et. al., 2012). Criticisms range from a lack of model testing, failures of the prescribed maximum credible magnitude in past PSHA (e.g. in the case of Tohoku) to the assumption of Poisson statistics, and even inherent problems with energy conservation in the PSHA method. For Klugel (2007), this amounts to a fundamental crisis for PSHA. Some of these criticisms may be overcome by modifications to the PSHA methodology, e.g. by using seismicity models that include short-term variations in their rates due to the time since the last large earthquake occurrence (Chan, 2013). Stirling (2013) observes that largest barrier to making PSHA effective in short term forecasting is the “inability to identify where/when major earthquakes are going to occur in areas/time periods of seismic quiescence. This is not a failing of PSHA methodology, but is one of the fundamental unknowns of seismology at the present time. “ This issue expressed by Stirling is of particular relevant to SCR seismicity, where earthquakes are clustered and infrequent. In this context, PSHA is still widely believed to offer a valuable, systematic integration of earthquake occurrence models (although crude) and ground motion models (although poorly constrained).