## 3 Results  
### Psha  
The spatial distribution of the PGA, computed via the logic tree approach (Figure 2) for a return period of 475 years, is illustrated in Figure 3a. The highest values were identified in close proximity to the coastline, near the towns of Nafpaktos and Aigion. The PGA decreased towards the north and reached its minimum of about 250 cm/s\({}^{2}\) at the NE edge of the study area. A maximum of \(\sim\)325 cm/s\({}^{2}\) was obtained approximately 5 km SSE of Aigion. The difference between the highest and the lowest values was 75 cm/s\({}^{2}\), which indicates that their variation was low to intermediate. The spatial distribution pattern of the PGA for a return period of 950 years was nearly identical (Figure 3b). A maximum of \(\sim\)400 cm/s\({}^{2}\) was found SSE of Aigion, meaning that there was an increase of 75 cm/s\({}^{2}\) compared to RP = 475 yr. The lowest value was about 300 cm/s\({}^{2}\), increased by 50 cm/s\({}^{2}\) from the respective value obtained for the return period of 475 years. Regarding the seismic hazard intensity measure of the PGV, the spatial distribution was similar to the PGA for a return period of 475 years (Figure 4a). A maximum of \(\sim\)18.5 cm/s was found toward the southern edge of Aigion, where the highest PGA was also determined. The lowest value persistently remained at the NE end of the study area, with an approximate PGV of 14 cm/s. In Nafpaktos, the PGVs were lower than in Aigion but higher than in Patras. The variation in the values was small, as the difference between  
Figure 3: Spatial distribution of PGA values for a return period (RP) of (**a**) 475 yr and (**b**) 950 yr.  
the highest and lowest PGV was only 4 cm/s. In Figure 4b, the spatial distribution of PGVs for a return period of 950 years is depicted. The highest PGV was about 24 cm/s, south of Aigion, and the lowest was 18 cm/s at the NE tip. The increase between PGVs for the two return periods was only 5 cm/s for the highest and 4 cm/s for the lowest values. Hazard curves were also generated for the three main WGoC city and towns; namely, Patras, Nafpaktos, and Aigion (Figure 5a). PGA values were calculated for a range of exceedance probabilities in 50 years to observe the increase rate for the PGA as a function of the return period. The hazard curves were proximal to each other, indicating that the level of seismic hazard was similar among the three sites. Patras presented a slightly lower PGA than Nafpaktos and Aigion. It could not be determined whether Aigion or Nafpaktos exhibited higher seismic hazard, as the PGAs were almost identical between the two cities. It is worth noting that the value of 1000 cm/s\({}^{2}\) was exceeded only for very small probabilities of exceedance, which implies that such extreme ground motions are unlikely to be reached. The last output of the PSHA calculations was the computation of Spectral acceleration (S\({}_{\text{a}}\)) values for periods ranging from 0.1 s to 2.0 s in the three aforementioned sites in order to construct uniform hazard spectra (Figure 5b). The S\({}_{\text{a}}\) curves for Patras, Nafpaktos, and Aigion were very similar to each other throughout all periods. This was reasonable in light of the close geographical distance among them. As illustrated in both PGA and PGV maps, the city and the two towns were adjacent to regions of comparable maximum expected ground motions. The maximum of the three spectra was about 500 cm/s\({}^{2}\) at a period of 0.25 s. The curves seemed to be nearly identical for periods above 0.9 s. Thus, at high periods, there was almost no difference between the three sites. Minor  
Figure 4: Spatial distribution of PGV values for (**a**) RP = 475 yr and (**b**) RP = 950 yr.  
deviations were detected in the period range [0.3, 0.5] s, for which Nafpaktos seemed to have slightly lower S\({}_{\text{a}}\) values than Patras and Aigion. The elastic design spectra proposed by the Current National Building Code (EAK2003) [109] and Eurocode 8 (Ec8) [110] were also plotted to investigate their relation with our results.