## 5 Conclusions
GRCS441: Trikforo source, associated with Trikforo and Sergoula faults, GRCS500: South Corinth Gulf source, associated with Sela, Lakka, w. Helike and e. Helike faults, GRCS524: Mamousisa source, associated with Piragaki and Mamousisa faults, GRIS502: west Helike fault source, also associated with Lakka fault, GRIS503: Aigion fault source, also associated with Fasouleika and Selianitika faults, Figure S21. Schematic representation of Band-1 and Band-2 zones, modified after [85]. The receiver at the surface is marked with S. The ABCD plane of vertically aligned microcracks is oriented towards the mean fast shear-wave polarization direction, \(\Phi\). Band-1 contains seismic rays traveling towards the seismic station at directions contained within the solid angle EFGH-to-S (blue),at angles between 15\({}^{\circ}\) and 45\({}^{\circ}\) (shear-wave window) on either side of the crack-plane. Band-2 contains seismic rays that travel within the solid angle ADEHG-to-S (red) towards the seismic station, i.e., within \(\pm\)15\({}^{\circ}\) from the crack-plane, Figure S22. Maps of the temporal evolution of the 2013-2014 sequence in the WGoC (Catalogue 1, all spatial groups except #3 and #10). The colours represent relative origin time (see labels on the colour-scale of each panel). (a) January - August 2013: the map shows sporadic activity inside the gulf, with the most significant cluster being the 2013 Helike sequence. (b) September 2013 - 14 July 2014: several clusters were observed at the western part of group #4, with activity going back and forth as shown with the red arrows. The dashed red ellipse shows a possible source of fluid injection. The black arrows show the direction (N100\({}^{\circ}\)E) and speed of seismicity migration or inferred fluid diffusion (see Figure 5). Seismicity gradually migrated eastwards at -0.13 km/day, activating the clusters with yellow colour (days 380-400). Fluid diffusion at a rate of 0.04 km/day towards N100\({}^{\circ}\)E precedes the triggering of the June 2014 sequence (dark blue), during which seismicity migration at 0.75 km/day was observed within the cluster (see also Figure A2). (c) 15 July - December 2014: bilateral seismicity migration observed in the spatial group #4, starting from the region marked with the red dashed ellipse (same as in panel b). Seismicity migration at a speed of 0.05 km/day towards N100\({}^{\circ}\)E between groups #8 and #6 is marked with a black arrow. The 7 November 2014 \(M_{w}\) = 4.8 event (green star) triggers seismicity mostly southwards, Figure S23. Annotated snapshot of the interactive 3D figure (File S1), showing the spatial group #6 and associated structure planes, along with selected surface fault planes (gray) extended downwards to the depth of 8 km at a 60\({}^{\circ}\) dip. The view is towards west. No vertical exaggeration has been applied, Figure S24. Annotated snapshot of the interactive 3D figure (File S1), showing the spatial groups #4 (green) and #5 (orange) and proposed associated structure planes. Selected surface fault planes (gray) are extended downwards to the depth of 8 km at a 60\({}^{\circ}\) dip. The view is towards north-east. No vertical exaggeration has been applied, Figure S25. Annotated snapshot of the interactive 3D figure (File S1), showing the 2013 Helike swarm (spatial group #9) and associated structure planes that were activated (blue). The surface fault planes (gray) of Pirgaki and Kerinitis faults are shown in gray. The view is downwards and towards NNE. Although the swarm is mainly associated with the north-dipping Pirgaki fault, it also contained events with oblique-normal focal mechanisms, likely related to NW-dipping structures sub-parallel to Kerinitis fault [6]. Conceptualization, G.K., V.K., G.M. and F.V. ; methodology, V.K., G.K., G.M. and F.V. ; software, V.K., G.K. and G.M. ; validation, V.K. and G.K.; formal analysis, V.K. and G.K.; investigation, V.K., G.K, G.M. and F.V. ; resources, V.K. ; data curation, V.K. ; writing--original draft preparation, V.K.