## 4 Discussion  
### Pockmarks Spatial Distribution and Morphometry  
A multidisciplinary survey consisting of high-resolution geophysical means and geochemical analyses provides new insights into the Patras Gulf Pockmarks Field (PGPF). In comparison to the 72 pockmarks recorded by the previous surveys [42; 57], in the present study, 115 pockmarks were recorded, of which 23 were covered by the harbour installations. Although the formation of new pockmarks after the construction of the new harbour (in 2015) cannot be excluded, the difference in the number of pockmarks is likely attributed to the limitations of the previous studies (instrumentation and sparse tracklines). The application of morphometric measurements showed that the PGPF consists of pockmarks variable in size, ranging from small and well-defined (8 m in diameter and 1 m deep) to large (260 m diameter and 20 m deep) ones. Their mean diameter is 72 m, and they are, on average, 7.3 m deeper than the surrounding seabed. These measurements are comparable to relative datasets from pockmarks obtained in the Eastern Mediterranean and worldwide [15; 27; 81; 82], though pockmarks can vary greatly in shape and size. The pockmark size dataset published by [PERSON] et al. [81] shows a compilation of data reported in 57 published papers. The compiled dataset shows that the pockmarks are characterized by a wide range of sizes, covering more than four orders of magnitude, where most of the pockmarks are 10-250 m in diameter and 1-25 m deep. Their mean diameter is 128 m, and their mean depth is 9.6 m. Based on that, the pockmarks of PGPF fall well within the range of the above-mentioned mean sizes [81]. The pockmarks of the PGPF also present a variety of shapes. In total, three main classes (unit, normal and composite) and two dominant geometric shapes (circular and ellipsoidal) are attributed to the pockmarks, though the field is limited in extent. Similar observations previously made in other examined areas show that the pockmark shape variety should be attributed to different styles of formation--due to their activity history and underlying structural framework--rather than different sedimentary/ hydrographic characteristics, which can be considered constant within the pockmark field area [83; 84]. The average density of the pockmarks in the PGPF is 50/km\({}^{2}\). Compared to the findings on other pockmark fields [84], the PGPF pockmark density (\(>\)5-10/km\({}^{2}\)) is classified as 'hydroanically active'. This density is higher compared with 18 pockmark fields in the central North Sea, which ranges between 4 and 29/km\({}^{2}\)[85]. It is also higher compared to the East Breaks pockmark field in the Gulf of Mexico (<15/km\({}^{2}\)) [15] and is similar to the Gulf of Maine (160/km\({}^{2}\)) [30] but lower than Snohvit hydrocarbon field in the SW Barents Sea (600-700 km\({}^{2}\)) [27]. Moreover, the spatial density is not homogenous but appears higher in the northern section (55/km\({}^{2}\)) (78/km\({}^{2}\), including the buried pockmarks) compared to the southern section (31/km\({}^{2}\)). [PERSON] et al. [1] suggested that the development of the pockmarks depends on the established migration path, which has further dependencies on features like sediment thickness, strength, permeability and faulting. The density patterns in the PGPF agree well with that observation. The highest densities (up to 100 pockmarks per km\({}^{2}\)) occurred at the proximity and southward of the AT.F, suggesting that the fault constitutes an important pathway for the upward gas migration in this field. Faults have been associated with fluid migration and seepage in the Barents Sea [27], Black Sea [25], Ireland [4], Marmara Sea [33; 34; 35] and Bohai Sea [26]. Furthermore, high pockmark densities (75/km\({}^{2}\)) are also present in the shallow part of the southern sector.