# Assessing Seismic Vulnerability and Pollution Risks of Wastewater Treatment Plants
## 3 Results and Discussion
* Exceedances of WWTPs' ISV As shown in Table 3, most WWTPs in Zone I and Zone II, totaling 70 WWTPs (60% of the entire sample), have negative exceedances. Meanwhile, 22 infrastructures (19% of the sample) have neutral values, and 24 infrastructures (21% of the sample) have positive values. This indicates that most WWTPs tend to have low ISV exceedances and are comparatively safer. Specifically, Zone I has twenty-five units with negative ISV exceedances (68% of all units in that zone) compared to nine units (24%) with positive ISV exceedances. Similarly, Zone II has 45 units (57% of all units in that zone) with negative ISV exceedances and 15 units (32%) with positive ISV exceedances. Zone I has more WWTPs with negative percentages, indicating that Zone I includes safer WWTPs. Authorities should pay attention to the high percentages of the twelve (12) units in Zone I and the thirty-four (34) units in Zone II that exceed the average ISV of all WWTPs (as shown in Table S2 in the SM). Table S2 in the SM details the increasing ISVs of each zone. * Exceedances of WWTPs' ISV-REF Finally, Figure S3b in the SM visualizes the zones of the SHM, incorporating a layer that depicts the exceedance of the ISV-REF compared to the average ISV-REF from all WWTPs. The map displays two (2) negative classes (\(-\)40 to 0%) and five (5) positive classes (0 to >100%). Positive exceedances of the percentages of WWTPs' ISV-REF indicate areas that require necessary measures, while negative percentages are considered safer. Units with low ISV-REF values are represented as small rhombuses, while those with the highest ISV-REF are represented as more significant, graduated rhombuses. As shown in Table 4, most WWTPs, totaling 19 units (51% of the entire sample from Zone I), exhibit negative exceedance of the ISV-REF, while positive exceedances are observed in 18 units (49%). Notably, Zone I has the highest values of the exceedance percentages, indicating that it includes safer WWTPs, whereas Zone II shows no clear trend in its values. Specifically, Zone II presents a range of ISV-REF exceedances, with 40 units exhibiting negative exceedances and 39 units exhibiting positive exceedances. Authorities should not overlook the high percentages of the eighteen (18) units in Zone I and the thirty-nine (39) units in Zone II that exceed the average ISV-REF of all WWTPs (see Table 5). This table provides an overview of the increasing ISV-REF for each zone. The outcome of this study includes individual or group estimations of the ISV, ISV-REF, and their exceedances compared to the average of the entire sample of WWTPs (Table S3 in the SM). The suggestion is that there are four cases where the research attempts to identify the most seismically vulnerable WWTPs. Assuming that high hazard levels correspond to ISV and ISV-REF values of 60% to 100% and 60% to >100% for their exceedances, an effort is made to color code the table to highlight high absolute or relative seismic vulnerability. The display of the number of colored cells for each unit should aid in identifying these cases and the most vulnerable WWTPs. Additionally, a high hazard is indicated when the exceedances of the ISV and ISV-REF are positive, as demonstrated in the last two columns in Table S3 in the SM. In particular, in the search for high seismic vulnerability, the paper reveals that four WWTPs accumulate four cases, seven units accumulate three cases, twenty-seven units accumulate two cases, thirty-one units accumulate one case, and forty-eight units accumulate zero cases (Table S3 in the SM). These results indicate that WWTPs with four cases exceeding 60% may exhibit high seismic vulnerability, followed by those three, two, one, and zero cases. Regardless of the current hazard levels identified in WWTPs, the questionnaire process must be repeated over time, as the parameters influencing the results may worsen. The regional grouping of data and the outputs derived from the Seismic Hazard Map (SHM) allow for meaningful comparisons between the present study and other studies in the literature.