# Assessing Seismic Vulnerability and Pollution Risks of Wastewater Treatment Plants
## 4 Conclusions  
As international and national laws require, prevention is achieved through quantitative and qualitative research. Qualitative estimations are essential for quickly assessing the seismic vulnerability of WWTPs. Seismic hazards in Greece depend on the zone to which an area belongs, with three seismic zones identified. Efforts were made to identify and estimate the spatial patterns of seismic vulnerability across the Greek regions. For this purpose, layers were constructed in QGIS for the country's coastline, the SHM, WWTPs, regions, the ISV, the ISV-REF, and their exceedances. Furthermore, a map was created showing the statistical population and the statistical sample of WWTPs. After excluding Zone III from the sample, the corresponding map presents 38 units from Zone I and 78 units from Zone II. Central Macedonia has twenty-one units in the sample, while Attica has two (2) units. The Regions of Peloponnese and Eastern Macedonia and Thrace have an ISV equal to 45% (indicating the highest vulnerability), while Epirus has an ISV of 34% (indicating the lowest vulnerability), according to expert judgments. Most WWTPs in Greece exhibit low vulnerability, with seventy-nine units having an ISV of 20-40%, thirty units having an ISV of 40-60%, and seven units having an ISV of 60-80%. Most WWTPs tend to be safe, exhibiting low exceedances of ISVs, as 70 units have negative exceedances of ISVs, 22 units have neutral values, and 24 units have positive values. These 24 units must not be ignored because the hazard is high. Zone I is estimated to have the safest units, in contrast to the units in Zone II. Also, the units in Zone II must not be ignored. According to the regions in Table 2, most units have a low or medium ISV-REF. The nine units in the seven regions that have high values of ISV-REFs (Table 2) and the seven units from the one hundred and sixteen of the sample that have high exceedings of ISVs (Table 3) must concern us. Considering exceeding the ISV-REF, the conclusion is that six units in Zone II and three units in Zone I have the highest values of the exceeding percentages. That indicates that most units are safe, but it must be not ignored that nine units exceed the suggested limit of 60% (Table 4). According to Table S3 in the SM, four WWTPs accumulate four cases (depicting high hazard), seven units accumulate three cases (showing severe hazard), twenty-seven units accumulate two cases (presenting medium hazard), thirty-one units accumulate one case (depicting low hazard), and forty-eight units accumulate zero cases (representing very low hazard). The main outcome of this study is the visualization of empirical findings regarding seismic vulnerability. The visualization of the seismic evaluation through maps ensures the protection of public health and the environment in a more effective manner. This study enhances the results of previous qualitative estimations of WWTPs' seismic vulnerability through a questionnaire based on expert judgment. The results are combined with the SHM, and the reference area is the whole territory. The experts' judgments for many questions are presented through the GIS platform and should be considered by scientists and policy decision makers. The survey has applied a specific time and presents an interesting challenge for further analytical or empirical research. Although the results depict many WWTPs in medium and high seismic vulnerability, there is a need to repeat the process in the future, as the results of future questionnaire parameters may worsen. The findings can highlight seismic vulnerabilities and guide more focused studies. Existing structures will need to be redesigned and analyzed based on the results of this study and subsequent detailed approaches. Authorities, decision makers, executors, auditors, and civil protection agencies can benefit from the current study and the accompanying maps, taking into account the hazards and incorporating immediate protective measures.