# Assessing Seismic Vulnerability and Pollution Risks of Wastewater Treatment Plants
## 3 Results and Discussion  
The present study utilizes previous outputs from the empirical method of \"Experts Judgement\" to estimate the seismic vulnerability of WWTPs. Future studies should place greater emphasis on the data used as inputs in the present study. For example, particular attention should be given to Zone III, which was excluded from the representative sample. This exclusion is significant, as that zone is classified as the highest hazard area in the country, according to the legislation. The main objective is to process these results. The numerical data and graphs from previous studies employing this empirical method enable the production of innovative hazard classifications on various topics using mapping processes. After data processing, the maps of the WWTPs are presented as a statistical population and sample (Figure S1 in the SM). The map shows the density of the units, which are represented as circles with a constant diameter for the statistical population and as asterisks for the statistical sample. The background of the SHM defines the graduation of the seismicity of the areas. The ISV map per region (Figure 2), the ISV-REF map per region (Figure S2 in the SM), and the maps showing the exceedance of the ISV and ISV-REF according to the Seismic Hazard Map (Figure S3 in the SM) are also presented. The paper assumes that WWTP percentages of 0-40% indicate low values, 40-60% indicate medium values, and 60-100% indicate high values. \begin{table}
\begin{tabular}{c c c c c c c c c} \hline
**Zone of Seismic Hazard Map** & \multicolumn{8}{c}{**Exceedance of ISV-REF (\%)**} \\ \hline  & \(-60^{\circ}\) to \(-40\) & \(-40^{\circ}\) to \(-20\) & \(-20^{\circ}\) to \(0\) & \(0\) to \(20\) & \(20^{\circ}\) to \(40\) & \(40^{\circ}\) to \(60\) & \(60^{\circ}\) to \(80\) & \(80^{\circ}\) to \(>\)100 \\ \hline I & 11 & 6 & 2 & 7 & 3 & 5 & 2 & 1 \\ II & 20 & 8 & 12 & 14 & 7 & 12 & 2 & 4 \\ \hline \end{tabular}
\end{table} 
Table 4: Amount of sample WWTPs, per Zone of the SHM and their inclusion in classes that exceed the ISV-REF. \begin{table}
\begin{tabular}{c c c} \hline
**WWTPs** & **Zone of the SHM** & **WWTPs** & **Zone of the SHM** \\ \hline \hline Erronopii\(-\)EL422001011 & I & Zachorne\(-\)EL2330110110 & II \\ Verola -EL120101016 & I & Megalopoli  
* WWTPs and their ISV The visualization in Figure 1 presents the Greek regions and their seismic vulnerability according to the statistical sample of WWTPs. A number of WWTPs in each region have been assigned percentages based on their average ISV (Table S1 in the SM) and are randomly colorized on the corresponding map. The region with the most WWTPs in the statistical sample is the Central Macedonia region, with twenty-one units, while the region with the fewest WWTPs is the Attica region, with two Units. The Central Macedonia region also comprises the country's second-largest city. Table 1 also presents the ISV values of the units. The most seismic vulnerable WWTPs are located in the regions of Peloponnese and Eastern Macedonia and Thrace (45%), while the least vulnerable seismic WWTPs are in Epirus and the Ionian Islands (34%), according to expert judgments. Across the entire sample of WWTPs, seventy-nine units have an ISV of 20-40%, thirty units have an ISV of 40-60%, and seven units have an ISV of 60-80%. It appears that most WWTPs in Greece have low vulnerability, as estimated by the experts. Figure 2 also presents the categorization of the ISV of the sample WWTPs per region according to two classes, 20-40% and 40-60%, for the average of the units' values. Nine (9) regions are estimated to have a 20-40% ISV, while four (4) regions have 40-60%. The regions of Attica, Sterea Ellada, Thessaly, Epirus, Central Macedonia, Peloponnese, Ionian Islands, North Aegean, and South Aegean appear to have low ISV percentages. In contrast, the regions of Western Greece, Western Macedonia, Eastern Macedonia and Thrace, and Crete seem to have medium ISV percentages.