## 5 Discussion and Conclusions
The tectonic analysis of the collected measurements during the fieldwork provided strong arguments of stress field changes along the NNE-SSW-trending fault zones, as two groups of structures were found on fault surfaces revealing lateral movement and extension along the NW-SE direction. As explained above, the lateral movement on the same fault surfaces is older than the normal one, which in turn coincides with arc-parallel extension. Finally, we refer to the Kastelli fault zone and in particular its southernmost segment (Lagouta fault), which is a west-dipping structure hosting a normal displacement movement with a strong left-lateral oblique component inherited by the dominating stress fieldduring Tortonian. It was exactly this structure that was activated during the Arkalochori earthquake, as the hypocenters of the sequence clearly delineate the above-mentioned fault surface. It is obvious that the two hypocentral clusters that have been described, form two discrete segments that belong to the same fault zone. It is the WNW-ESE-trending Nipiditos fault that seems to be the structural reason for this segmentation. The northern cluster is formed on the surface of the Kastelli fault and the southern cluster on the Lagouta fault (Figure 10). Even though all events belong to the same sequence, it is rather clear that the northern cluster is located at more shallow depths compared to the southern cluster. Concerning the seismological data, the 27 September \(M_{\rm w}=6.0\) mainshock was a reminder that strong earthquakes do occur onshore Crete. It was preceded by a rich sequence of over 700 foreshocks that was considered a swarm, due to its largest event occurring halfway through 24 July. However, it did not cause much concern at the time, as similar swarms have been known to occur elsewhere in Greece, without leading to a strong event of \(M_{\rm w}\approx 6.0\), unlike the case of the Arkalochori earthquake. The herein analysis highlights the importance of local seismological networks to the reduction in location uncertainties. The applied double-difference relocation has managed to improve the relative locations of the foreshock epicenters, which are concentrated in the vicinity of the 27 September mainshock, although their hypocenters could not be adequately constrained. The mainshock apparently broke a large asperity of a west-dipping normal fault and distributed stresses towards its northern and southern edges, triggering aftershocks mainly at two large groups, separated by a spatial gap, where the asperity was located. Similar cases have been previously reported in other significant earthquakes on normal faults in Greece, including the 1999 Athens [79, 80], the 2017 Kos [81, 82], and the 2020 Samos [83, 84, 85, 86] earthquakes. The herein presented relocation analysis of the sequence during its second period, i.e., with data from the temporary local network that was deployed by GI-NOA, permitted the detailed delineation of the main activated structures which could be related to mapped faults on the surface, allowing for a small degree of listicity, as well as contingent smaller antithetic, conjugate faults at depth. The spatiotemporal evolution of the sequence indicated triggering of seismicity throughout most of the aftershock zone soon after the mainshock, attributed to coseismic stress transfer, followed by slower migration towards its outer edges, indicating possible after slip. Based on the post-earthquake fieldwork, both activated fault segments (Kastelli and Lagouta) did not show any signs of surface raptures along their traces, which agrees with the interferometric findings. A straightforward interpretation of horizontal motion patterns derived from the DInSAR analysis points out that the observed migration of motion during the post-seismic period (interferograms of different temporal spans) is mainly in agreement with the aftershock distribution and clustering, and to a lesser extent linked to actual co-seismic motion patterns.