## 4 Results
### Synthesis of Strain Results
#### 4.1.3 Area Strain (AS)  
Two distinct AS types are distinguished: (i) dilatation, which is directly related to extension, and (ii) compaction, which is directly related to compression. Compaction is the predominant form of strain in the North Aegean Sea region, while the nano-strain values for AS range from \(-\)1180 (compaction) to 970 (dilatation) (Figure 6a). The dilatation encompasses a larger region (Figure 6b); the most significant values are documented in the eastern and northeastern parts of the North Aegean Sea. Samothraki Plateau and western NAB have smaller but notable dilatation values. Most compaction occurs in the southerly area of the North Aegean Sea (NAB and NAT). In particular, the CAT exhibits remarkably low values. Compaction is limited to the north of the NAB and NAT, showing a slight presence in the northeast of the North Aegean Sea and along the eastern coast of Thessaly. In a case of a vast contrast between dilatation and compaction, extensional or compressional tectonics occur, respectively. However, shear tectonics are documented in a  
Figure 5: Maximum Shear Strain (MaxSS) in the wider North Aegean region: (**a**) MaxSS values (red circles) of all triangles, constructed within the three study areas; (**b**) MaxSS values grid, based on the interpolation (kriging) geostatistical analysis. Dark lines in (**b**) are faults (see also Figure 2). case of similar dilatation and compaction values. For instance, the broader NAT region is characterized by high dilatation and compaction values, defining a more complex setting, as the two strain types do not extend uniformly or equally. Figure 6: Area Strain (AS) in the wider North Aegean area: (**a**) Dilatation (blue circles) and compaction (red circles) calculated values; (**b**) dilatation values grid, based on the interpolation (kriging) geostatistical methodology; and (**c**) compaction values grid, based on the interpolation (kriging) geostatistical methodology. Dark lines in (**b**,**c**) are faults (see also Figure 2). Accordingly, the AS results of the Strymon basin reveal a dilatation dominance over compaction (Figure 5a), with values ranging from approximately \(-600\) (compaction) to \(2750\times 10^{-9}\) (dilatation). Even though the dilatation type dominates in the Strymon basin (Figure 6b), it partially coexists with compaction, indicating shear occurrence [17]. Specifically, the greatest concentrations are only documented within the Strymon basin area, especially along the eastern margin and the northwestern part of the Strymon basin. Concerning the high-value concentrations of compaction (Figure 6b), they are predominantly documented at the eastern Strymon basin boundary [17]. The difference between dilatation and compaction defines extension (dilatation \(>\) compaction) or compression (compaction \(>\) dilatation), whereas comparable values indicate shear tectonics [71]. The Strymon basin is predominantly characterized by dilatation over compaction; nevertheless, the compaction occurrence is noteworthy, indicating that despite the dilatation dominance, a remarkable shear component is documented, leading to oblique-slip, normal faulting. A typical example is the southernmost part of the Strymon basin, which is adjacent to the North Aegean Sea and potentially affected by the corresponding strike-slip tectonic regime. Regarding the Thessalian basin area, it exhibits AS values that vary from \(-420\) to \(360\) nano-strain [72], implying occurrences of both dilatation and compaction (Figure 6a,b). The phenomenon of compaction is primarily spotted at the western boundary of Thessalian basin, where the absolute strain (AS) exceeds \(100\) nano-strain. However, there are also some areas in the central part, where the absolute strain ranges between \(50\) and \(150\) nano-strain. The dilatation shows a greater dispersion when higher values are considered, specifically with values exceeding \(200\) nano-strain in the southeastern Thessalian basin [72]; the maximum dilatation is observed to the south of the Thessalian basin.