## 3 Results
### Spatial Distribution of Seismicity
Black dashed lines at the top of the cross-sections indicate the position of mapped active faults, with a typical down-dip extension at 60\({}^{\circ}\), while coloured dashed lines indicate the inferred dip of activated structures at depth, according to the hypocentral distribution and/or focal mechanisms. Fault name abbreviations on the map, aKa: Ano Kastritis f., Pt.f. : Panachaikon transfer-fault, RPfz: Rion-Patras fault zone, Psa: Psaubpyrgos f., Plat: Platanitis f., Mar: Marathias f., Sergoula f., Kal: Kalliteha f., Triz: Trizonia f., Sel: Selianitika f., Fas: Fasouleika f., wHe: West Helike f., Pir: Pirgaki f.  
Another important profile is presented in the cross-section c\({}_{1}\)-c\({}_{2}\) of Figure 4, which includes groups #6 and #9. The 2013 Helike swarm (group #9, blue) occurred mainly in the depth range of 8-10 km. A detailed analysis of this swarm [6] has revealed focal mechanisms associated with both north-dipping normal faulting and oblique-normal faulting. Such kinematics have also been observed for the 2001 Agios Ioannis swarm [4; 8; 49], associated with the northwest-dipping Kerinitis fault. The extension of the north-dipping fault plane of the 2013 Helike swarm to the surface is traced near the junction between Pirgaki and Kerinitis faults [6]. The relation of these faults to the structures activated during the 2013 Helike swarm is presented in Figure S25 (see also the provided interactive Matlab figure; File S1). It should be noted that the Pirgaki fault is likely a branch of the Mamousia seismogenic source (GRCS524 in [14]; Figure S20). The southern seismicity in group #6 (red) is mostly part of the aftershock sequence of the 7 November 2014 \(M_{\rm w}\) = 4.8 event and appears to be associated with the west Helike fault. The focal mechanism of the mainshock suggests a northwards dip of 30\({}^{\circ}\), while the hypocentral distribution of its aftershocks (south of its epicenter) corresponds to a roughly \(\sim\)40\({}^{\circ}\) dip. The latter could indicate some degree of lstricity, or the existence of multiple smaller activated structures within the seismogenic layer, each dipping at a higher angle (e.g., 60\({}^{\circ}\)). Seismicity of group #6 extends further north, with the focal mechanism of a smaller event that occurred on 28 January 2013 having a dip of 28\({}^{\circ}\). This low dip angle is similar to that of the northern part of group #8 (brown), as well as of the deeper part of group #7 (yellow). It is noteworthy, however, that when examined in a N100\({}^{\circ}\)E cross-section (Figure S15, along the Kamarai fault zone), there appears to be a vertical offset between these shallow dipping segments of groups #4, #8 and #6, tending to deepen from west to east (see also File S1). This is likely related to the _en chelon_ faulting configuration at the southern shoulder of the WGoC. Other parts of seismicity (Figure S13) include the northern groups #5 (orange, between Nafpaktos and Pyrgos, i.e., station PYRG) and #2 (magenta, near Eratini; Figure 1). Both are associated with sparse seismicity on a shallow-angle, north-dipping plane, reaching depths larger than 10 km below the northern coast. Group #1 (black), likely related with the deeper and almost flat sector of the South Corinth Gulf composite seismogenic source (GRCS500 in [14]; Figure S20), follows the trend of group #2 southwards at depths of 8-12 km. At the eastern margin of the study area, the isolated cluster #3 (cyan) is associated with a nearly dip-slip faulting type (Figure 4, Table 1) on a sub-vertical WNW-ESE-trending fault, slightly tilted northwards. Seismicity in the miscellaneous group #10 (gray) includes activity around the margins of the study area or deeper than 15 km. The latter is the case for events southwest of group #4, in the form of small clusters located at depths of \(\sim\)17-22 km. Some deeper events are also located below Aigion, including an \(M_{\rm w}\) = 4.0 earthquake that occurred on 28 April 2013 at a depth of 47 km with its epicenter offshore, east of group #9.