# GIS-Based Optimal Route Selection of Submarine Cables Considering Potential Seismic Fault Zones
## 1 Introduction
[32] conducted a full-scale experiment and performed a comprehensive parametric study to numerically investigate the problem of fault-cable intersection in the case of strike-slip faults, considering quasi-static loading conditions. [PERSON] et al. 2016 [33] examined the problem of fault-cable intersection utilizing an analytical optimization approach considering, as objectives, both cost and cable breaking probability. In contrast, significant experimental [34; 35; 36], numerical [37; 38; 39] and analytical [40; 41; 42] research has been conducted to address the problem of fault-pipeline intersection. Therefore, further research is required for the seismic design and optimal route selection of submarine cables, assessing whether the proposed routing could effectively cross a (seismically) geologically hazardous area by quantifying the criticality of the potential problems (i.e., exceedance of allowable strains of the cable). Recently, the authors facilitated the optimal route selection of large-scale engineering projects (such as natural gas pipelines) subjected to earthquake-triggered geohazards (i.e., seismic fault rupture and submarine slope instability) through the development of a GIS-based smart decision-support tool [26; 43]. The structural performance of the pipeline was evaluated through finite-element analyses and (semi-)analytical models and the corresponding results were combined, in the form of an advanced criterion, with the LCPA technique within the GIS environment. The current work presents an upgraded version of the aforementioned smart tool, which aims to achieve the optimal route of submarine fiber-optic and power transmission cables, taking into account--among other criteria--the quantitative assessment of the geohazard of fault rupture and the consequent cable distress. The main novelty of the developed smart tool is that it efficiently combines different software (i.e., for the geospatial process of optimal route selection and for the numerical analysis of the cables), supporting tools (i.e., Python scripts) and decision-making methodologies (MCDM). More specifically, the GIS-based LCPA technique is successfully combined with AHP to efficiently exploit all possible routing alternatives of submarine cables in seismically geologically hazardous regions, such as the wider Mediterranean region. In particular, various scenarios have been considered by assigning different weight values to the adopted design criteria which include active fault zones. In addition, a different rating score has been assigned to each fault zone in order to assess more realistically their potential impact on the examined cables as much as possible. Analogous ratings are given to the other design criteria, i.e., seabed inclination and bathymetry. It is noted that in previous studies, where AHP was combined with GIS for the route selection of CLs, earthquake-related geohazards, such as fault ruptures, were either completely ignored [2; 16], or treated as absolute barriers (i.e., could not be crossed) without assessing the structural distress of a crossing CL. Consequently, their weight values were exemplified by defining them as \"\(\infty\)\" [15]. This deficiency is alleviated in the current study, as efficient finite element (FE) numerical models for both energy and telecommunication submarine cables have been developed and have been integrated in the proposed GIS-based decision tool to realistically address the problem of fault-cable intersection. These FE models constitute another valuable contribution of the present work, as to the best of the authors' knowledge, there are only a very few relevant studies addressing this very important and demanding problem of offshore cable intersection with tectonic faults. The applicability of the smart tool is verified via its implementation in three real case studies (i.e., an offshore telecommunication (fiber-optic) cable and two power transmission cables) in the southeastern Mediterranean Sea.