# Assessing Seismic Vulnerability and Pollution Risks of Wastewater Treatment Plants
## 3 Results and Discussion
It appears that most regions have a low ISV and should not face significant seismic vulnerabilities, according to experts' judgment. Regions with medium values of 40-60% do not reach the potentially highest dangerous values of 60-80% and 80-100%, where measures must be implemented immediately. Consequently, based on this assumption, high seismic vulnerability does not affect the WWTPs in any region. Obviously, these assessments should be taken into account by the authorities. * WWTPs and their ISV-REF Investigating the whole sample of WWTPs for potential pollution in soil and water resources, seventy-nine units have a 20-40% ISV-REF, twenty-eight units have 40-60%, and nine units have 60-80% (Figure S2 in the SM). This output illustrates that experts estimate that most WWTPs have low vulnerability to potential soil and water pollution in Greece. Figure S2a in the SM visualizes the zones of the SHM, with an added layer of the ISV-REF. Each estimation of a WWTP's ISV-REF is categorized into four (4) classes (produced classes: 0-80%). Units with a low average ISV-REF are represented as small diameter circles, while those with a higher average ISV-REF are represented with larger, graduated diameters. Table 1 shows that most WWTPs (80 units, representing 69% of the entire sample) located in Zone I and Zone II have a low ISV-REF (0-40%). Meanwhile, twenty-seven infrastructures (23% of the sample) have medium ISV-REF values (40-60%), and nine infrastructures (8% of the sample) have high ISV-REF values (60-80%). Most WWTPs are estimated to have low percentages of ISV-REF percentages. Specifically, Zone I has the most units (26 units) with low ISV-REF percentages, while Zone II has the most units (54 units) and also has low ISV-REF percentages. Authorities should not overlook the high ISV-REF percentages of the nine (9) units, which include three units from Zone I (Patmos, Krestena, Drama) and six units from Zone II (Malesina, Anogeia, Amaliada, Hersonisos, Nea Roda, Kokkari). The categorization of the ISV-REFs for the sampled WWTPs by region is illustrated in the map in Figure S2b in the SM. The values for each region are calculated as the mean
of the units' values within that region. Two classes (20-40% and 40-60%) are depicted for visualization. As described in Table 2, the ISV-REF for 31 WWTPs is 0-20%; for forty-nine units, it is 20-40%, for twenty-seven units, it is 40-60%, and for nine units, it is 60-80%. These percentages indicate that experts estimate that most WWTPs should have an ISV-REF of 20-40%, indicating low seismic vulnerability. These low ratings are notably found in Greece's most seismo-tectionically active area, the Ionian Islands (in Zone III). This can be explained by the fact that Corfu, the only island in the Ionian Islands region included in the sample, belongs to Seismic Hazard Zone II. Attica and Central Macedonia, which include the capital and subcapital of the country, have low ratings (0-20%). This is logical, as these regions have large, well-organized units that are constantly supervised by many specialized personnel and utilize more reliable machinery. Notably, the region of the Peloponnese, which includes the third most populated town in the country, has a medium ISV-REF (40-60%). This should be highlighted to the authorities for further attention and action. Figure S3a in the SM visualizes the zones of the SHM, with an additional layer showing the exceedance of ISVs compared to the average ISV of all WWTPs. The map displays a gradient with two (2) negative classes (\(-\)40 to 0%) and five (5) positive classes (0 to >100%). Positive exceedances in the percentages of WWTPs' ISV indicate areas where necessary measures are required, while negative percentages suggest more excellent safety. Units in Zone I and Zone II with low ISV values are represented as small rhombuses. In contrast, units with higher ISV exceedances are depicted as more significant, graduated rhombuses.