## 2 Geodynamic Setting and Tectonic Pattern
The Belles-Kerkini fault zone  
The Belles-Kerkini fault zone is characterized by remarkable morphological features, while the recent tectonic activity is subjected to the dominant NNE-SSW extensional regime of the wider area [29; 39; 41; 71; 72; 73]; the Belles-Kerkini fault zone is longer than 40 km [74]. According to the initial morphotectonic observations [75; 76], the Mt Belles-Kerkini was considered as an E-W-trending horst (Plioene-Quaternary), delimited by two adjacent grabens, expanding northerly and southerly, respectively. The Quaternary fault activity affected the Pliocene alluvial deposits, lying along the alpine bedrock-composed foothills. In particular, geomorphological features such as well-developed fault-scarp zones, the deposition of new generations of fans upon the older ones close to the fault zone, post-depositional gully erosion, etc., resulted in the conclusion that the western part of Mt Kerkini is more active than the eastern part. Later on, [PERSON] et al. [41] separated the fault zone into two fault segments, i.e., an 18 km-long segment to the west and a 24 km-long segment to the east. The former, consisting of two subparallel strands, dips to the south in a steep angle, and, westerly, it merges with an ENE-WSW-trending fault, extending up to Doirani Lake. The latter separates the sediments of Strymon basin from the alpine metamorphic rocks (Mt Belles-Kerkini). The authors also observed that the Petritsi fault intersects the NE-SW (to ENE-WSW)-trending faults north of Petritsi village. 4. The Sochos fault zone  
The Sochos fault zone forms a smaller intermontane basin on the Mt Vertiskos crystalline mass [77; 78]. [PERSON] et al. [41; 79] reassessed its location and length and characterized it as an active structure. It consists of at least two segments, named the Sochos and Mavrouda faults, in a right-stepping geometry [79; 80]. [PERSON] et al. [41] assessed that  
Figure 2: Typical wine-glass valleys, related to the Tholos–Nea Zichni (TNFZ) fault zone, located at the eastern boundary of the Strymon Basin. The red solid line indicates the linear fault trace. White lines show the incised wine-glass valleys indicating football uplift. Overall, the fault trace separates uplift from subsidence, controlling the present-day sedimentation processes, and also demonstrating that the fault is active. this fault zone was activated on 29 September 1932 (M6.2, according to [PERSON] and [PERSON] [47]), and its isoseismals were parallel to the fault zone [81]. The Serres fault zone (SFZ) lies along the margin of the corresponding basin, i.e., the Strymon basin, while it consists of discontinuous fault traces of a general E-W direction downthrowing to the south. The SFS is located along the central-east margin of the Strymon basin, disrupting its general NW-SE trend. The eastern part of the fault zone shows a slight change of direction to the ESE, toward the Tholos-Nea Zichni fault zone. This part is shown on the respective 1:50,000-scale geological map of the Institute of Geology and Mineral Exploration (IGME) [82] as affecting the Quaternary sediments that lie along the foothills of Mt Menikion. The western, E-W-striking part of the fault zone, passing by and through the city of Serres, was later mapped by [PERSON] [83], [PERSON] [84], and [PERSON] et al. [41], who characterized it as active. In fact, the part which passes through the city of Serres is the westmost part of the zone showing an ENE-WSW orientation. Normal dip-slip slicken lines overprinted on older strike-slip ones were found on the main boundary faults separating the crystalline basement of Mt Menikion from the post-alpine sediments of the basin [84]. The Drama fault zone (DFZ) shows common properties with SFZ, as they both trend towards E-W, downthrowing to the south, and are comprised of discontinuous fault traces. However, a difference between them is that the DFZ bounds entirely the northern part of the Drama basin against the Mt Phalakron.