## 3 Results
### Pockmark Field
#### 3.1.1 Pockmark Distribution, Size and Shape
\begin{table}
\begin{tabular}{c c c c} \hline \hline  & **Total** & **North Sector** & **South Sector** \\ \hline Total Number & 92 (+23 buried) & 55 (+23 buried) & 31 \\ No of Unit Pockmarks & 9 & 4 & 3 \\ No of Normal Pockmarks & 54 & 35 & 15 \\ No of Composite Pockmarks & 29 & 16 & 13 \\ Diameter (m) min–max & 8–260 (72) & 8–200 (65) & 12–260 (90) \\ (mean) & 25–806 (218) & 25–637 (207) & 38–806 (260) \\ Volume (m\({}^{3}\)) min–max (mean) & 165–360,682 (22,247) & 165–97,094 (15,102) & 181–360,682 (38,654) \\ Relative Depth (m) min–max & 1–19.3 (7.3) & 2.5–15.3 (7) & 1–19.3 (8.7) \\ (mean) & 5–46 (26) & 5–46 (26) & 6–41 (29) \\ Relative Depth—Diameter ratio min–max (mean) & 0.03–0.47 (0.13) & 0.03–0.47 (0.14) & 0.04–0.26 (0.11) \\ Circular & 37 & 23 & 8 \\ Elliptical & 55 & 32 & 23 \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Descriptive measurements of the PGPF pockmarks. Figure 3: **(a)** Bathymetric map of the PGPF. The map also shows the location of Agia Triada Fault (AT.F) and the location of the largest pockmark ’P4’. Dotted red lines separate the two sectors (North and South) of the pockmark field and delimit areas of high pockmark density (HD1 and HD2); red arrows indicate the location of the pockmarks north of AT.F discovered in the present study. **(b)** The bathymetry of the PGPF before the construction of the harbour was derived from single beam data (cell size 2.5 m). The dashed polygons delineate the areas of PGPF covered by the harbour installations. **(c–f)** Detailed bathymetry showing **(c)** unit pockmarks; **(d)** a cluster of normal and small composite pockmarks deliminated by black line; **(e)** the largest composite pockmark of the field; **(f)** a pockmark “chain” of linearly arranged pockmarks deliminated by black line. Descriptive measurements for the 92 pockmarks are summarised in Table 1. All over the PGPF, the pockmarks are 7.3 m on average, deeper than the surrounding seafloor, while there are pockmarks up to 20 m deep. Most of the pockmarks have been formed between 20 and 43 m water depth, and their occurrence shows an almost moderate correlation (R = 0.4) with the seafloor depth. However, the larger pockmarks exhibit a tendency toward greater depths of water (Figure 4a). Most of the pockmarks extend for less than 8000 m\({}^{2}\); the deepest and most extended pockmarks are usually found in the southern sector of the field. Over 60% of the pockmarks have a perimeter between 100 and 300 m, and the mean field diameter is 72 m. The relation between pockmark depth and rim diameter is strong (R = 0.67), suggesting that most are not scale-dependent features (Figure 4b). A similar correlation has been observed in the Belfast Bay pockmark field [28]. The seafloor slope of the PGPF ranges from 5\({}^{\circ}\) to 46\({}^{\circ}\), with the low values (1.5\({}^{\circ}\)) corresponding to the background seafloor and the maximum values (up to 46\({}^{\circ}\)) to the pockmark sidewalls (Figure 4c). The mean sidewall slope is 26\({}^{\circ}\) and is much higher than other pockmark fields (e.g., Belfast Bay [28]). There is a significant positive relationship between the sidewall slope and the relative depth, with the wider pockmarks showing steeper slopes (Figure 4c). In PGPF, pockmark side walls are usually steeper than the proposed angle of repose for submarine sedimentary deposits, which ranges between 20\({}^{\circ}\)[59] and 12.5-17.5\({}^{\circ}\)[60]. The mean volume of the pockmarks is 22,247 m\({}^{3}\), with the smallest pockmark approximately 165 m\({}^{3}\) and the largest 360,682 m\({}^{3}\). Based on the difference between present-day bathymetry and a hypothetical bathymetric model without the pockmarks, the total volume of the PGPF is estimated to be about 2.1 \(\times\) 106 m\({}^{3}\), suggesting that a large volume of sediments has been displaced by the pockmark activity. An analysis of the directions of the major axes of the ellipsoidal pockmarks showed that these are not randomly oriented (Figure 4e).