# GIS-Based Optimal Route Selection of Submarine Cables Considering Potential Seismic Fault Zones
## 4 Discussion  
Results from Figure 7a reveal that the eastern Mediterranean Sea is characterized by deep and ultra-deep waters, reaching depths of up to 4000 m. Figure 7b illustrates that the central part of the examined area is mostly characterized by a very smooth seabed inclination, whereas steep slopes are located near the coasts of southwestern Greece, southern Crete, Rhodes and Turkey, thus, forming a wide basin. Figure 7c,d demonstrate that the eastern Mediterranean Sea is a seismic-prone and tectonically active region, as intense seismicity, especially near the Cretan coastline, and several fault zones can be easily observed. As a consequence, a CL crossing these areas would be subjected to various offshore earthquake-related geohazards, including seismic fault rupture and potential submarine landslides. However, at this point it is important to note that local site conditions constitute a critical factor that play a key role in the earthquake-triggered geohazard of seismic fault rupture and the structural response of the crossing CL. On the one hand, the presence of soft sediments that cover the ruptured bedrock might have a beneficial impact on the kinematic distress of the CL, as they tend to absorb the abrupt bedrock displacements, thus leading to a smoother displacement profile at the seabed. On the other hand, an outcropped fault (i.e., without the presence of overlying soft sediments) may have an unfavorable impact on the structural behavior of the CL, as it has been evidenced in the case of onshore pipelines [70]. According to Figure 8, medium-to-thick sediments are located at the central part of the Mediterranean Sea and near the delta of the Nile River in the sea area north of Egypt. Conversely, the areas near the coasts of Crete, Libya, eastern Egypt and Cyprus are characterized by very thin or even none overlying soft sediments. In a previous version of the developed smart tool, [PERSON] et al. [43] selected the optimal route of an offshore gas pipeline connecting the island of Crete to Cyprus. The optimal route was crossing the East Mediterranean ridge and the role of sediments, which had been assumed to cover the ridge, was taken into account via an extensive numerical investigation. The consequent structural distress of the crossing CL was assessed and the problem of a pipeline-blind-fault intersection was effectively addressed. The authors revealed that the examined facility could safely cross the East Mediterranean ridge due to the beneficial impact of the overlying seabed sediments. Herein, the more adverse problem of an outcropped-fault-cable intersection has been examined. The fault zones near the island of Crete (i.e., Cretan-Rhodes ridge, Hellenic trench), the Herodotus trough, as well as the fault zones near Cyprus (i.e., West Cyprus arc, South Cyprus trench) have been assumed to be covered from zero to very thin sediments. Consequently, they have received a greater rating score during the application of the smart decision-support tool, compared to the East Mediterranean ridge, as shown in Tables 3 and 4. It is noted that the Cretan-Rhodes ridge, as well as the seismic fault zones near Cyprus have not been taken into account in Case Study 1 (telecommunication cable between Crete and Libya), whereas Case Study 2 (power cable between Crete and Egypt) has not considered the Herodotus trough and the seismic fault zones near Cyprus. This is due to the fact that the aforementioned fault zones had no effect on the optimal route selection process. Finally, it is important to mention that in engineering practice, minimizing the fault-cable intersection length (i.e., vertical crossing) is expected to reduce the risk of cable structural failures [5]. Apart from the seismically active fault zones, bathymetry and seabed inclination have also been selected as basic criteria for the optimal route selection of the submarine cables. As presented in Tables 3 and 4, the applied rating score is in line with the engineering practice in the field of submarine cable routing.