## 2 Materials and Methods
### Seismic Scenarios
This approach has been also followed by other authors for this mainshock [86; 88]. Finite-fault discretization into smaller subfaults was performed using the empirical relationship proposed by [PERSON] and [PERSON] [91] (Equation (1)):  
\[\log\Delta\mathrm{I}=0.4\mathrm{M}-2, \tag{1}\]  
where \(\Delta\mathrm{I}\) is the length of each subfault and M is the moment magnitude of the mainshock. The \(\Delta\sigma\) is a parameter closely related to the actual stress drop and slip velocity due to an earthquake occurrence, but it does not include the natural context of stress drop [92]. It is generally considered to weakly scale with moment magnitude, but in a more regional extent their interconnection appears to be more profound [93]. It was determined by employing an iterative procedure, comparing the synthetic ground motions with recorded ones, as well as with estimated peak values from well-established GMPEs [94; 95] appropriate for the study area. The \(\Delta\sigma\) value of 56 bars, which is routinely used as a mean value for earthquakes in Greece [96; 97], was used initially and, afterwards, various other values were tested to find the best fit. Ultimately, \(\Delta\sigma\) = 30 bars was deemed appropriate and was adopted in the simulations. This deviation from the mean value was foreseen, given that low stress drop has been documented for this earthquake [98], as well as for the study area, especially in comparison with the eastern part of the gulf where stress drop values appear to be larger [99]. Regarding the path effects, the geometrical spreading model, as described by [PERSON] [100], was adopted, which divides the slope of the attenuation relation in three distance intervals (<70 km, 70-130 km, and >130 km), reflecting the dominant type of wave in the seismic signal. The anelastic attenuation, on the other hand, is described by the quality factor proposed by [PERSON] [101] for the broader Aegean region (Equation (2)):  
\[\mathrm{Q(f)}=100\mathrm{f}^{0.8}, \tag{2}\]  
Lastly, to account for the local site conditions for synthetic ground motions, the average \(\kappa_{0}\) value of 0.044 for class C (NEHRP) sites in Greece [102] was adopted, along with the corresponding amplification factors. The selection of class C soil characterization was based on local soil data (e.g., Vs30 profiles) for the major cities in the area and geology data from the locations of the available seismic stations. In order to calibrate and validate our results, the GMPEs of A14 and B14 were employed. Both were derived using strong motion datasets from Italy, Greece, and Turkey. After validating the basic stochastic simulation parameters for the study area, three well-studied seismogenic faults (Panthopyrgs Fault (PT); Helike Fault (HF); Trizonia Fault (TF)) were selected to assess the worst-case earthquake scenarios (Table 2, Figure 1). Giventhe limited extent of the area under study and the consistency in the seismotectonic regime, we assumed that path and local site effects were properly constrained from the Aigion 1995 simulations. It was, therefore, only necessary to define the seismic source parameters and, particularly, the fault dimensions and geometry, as well as the M\({}_{\rm max}\). Fault characteristics were adopted from various studies (see Table 2 caption) and the M\({}_{\rm max}\) was calculated following the approach described by [PERSON] et al. [103], which is a slightly different version of the method proposed by [PERSON] et al. [104]. The adopted approach combined various scaling relationships between magnitude and rupture length with the maximum observed magnitude obtained from historical data. The finally adopted M\({}_{\rm max}\) (Table 2) was weighted and acquired through the combination of all relative M\({}_{\rm max}\) values, along with their standard deviations. In our assessment, the scaling laws from [105; 106; 107; 108] were used. Furthermore, the definition of the hypocenter position and the slip distribution onto the fault plane is a crucial step in stochastic simulations.