## 5 Discussion and Conclusions  
The recent Arkalochori earthquake sequence, which was recorded before and after the mainshock (27 September 2021), seems to be a quite prominent opportunity to discuss the contemporary tectonic regime of MB. The latter has a very significant geotectonic placement in the context of the African plate subduction that takes place under the Aegean microplate, as it is an onshore post-orogenic basin in the vicinity of the active Hellenic Arc [4; 73]. Crete is at a crucial location right above the subducting slab and it is more than certain that the impact of the plate convergence is imprinted on the island, at all scales [74]. The fault pattern that was mapped in detail revealed the different generations of fault-block movements, as a result of the stress field changes since the integration of the Alpine nappe pile buildup [1]. Several direction changes of the main stress axes have been imprinted on the fault structures and the surface morphology [3]. It seems that the easternmost area of MB had been under N-S-trending compression during the orogen buildup, followed by an N-S-trending extension during the slab rollback and the orogen collapse through the detachments' operation (either north or south dipping) [1; 8; 10; 75]. From an evolutionary point of view, we argue that after the generation of the nappe pile on Crete and the south-dipping detachment fault, several almost E-W-trending fault zones were activated (as segments of the south-dipping detachment) since they crosscut rocks that belong to different Alpine units. These fault zones remained active until after the end of late Serravallian, when the deposition of the lacustrine Viannos sediments was completed, as large fault blocks comprising Serravallian age successions are found tilted towards NNE. A transtensional geotectonic regime, which seems to be dominating the entire Aegean microplate [76], is expressed on the Cretan territory by nearly NNE-SSW-trending strike-slip fault zones [20; 77] and one of them crosscuts the central area of the island and simultaneously was acting as the marginal structure of the HB-MB system [2]. It should be mentioned that the main fault zones that were found along the eastern margin of MB are striking NNE-SSW, NW-SE, and E-W. The kinematic analysis of these data showed that most of the faults that were activated after the Early Miocene were either normal or strike-slip faults with left-lateral movement components [3]. According to this analysis, the NNE-SSW-trending shear zone was also affecting the previously generated E-W-trending fault zones, which were inherited by the Early Miocene N-S extensional period, when the south Cretan detachment was still active [1]. The impact on these E-W-trending structures is crucial as they seem to have been segmented and some of the segments have been reactivated during or shortly after the Pliocene (e.g., Nipiditos fault). Specifically, during Tortonian, while the sediments of the Ampelouzos formation were still depositing, the dominating stress field had a strong left-lateral component, which is evidenced by the syn-sedimentary structure analysis (Figure 6b). The stress field seems to be active during the Tortonian since the syn-sedimentary faults were deforming the Ampelouzos unit strata (see Section 2.2 for lithology description), which were deposited before 10 Ma in a coastal to shallow depth marine environment [78]. A strong case scenario, considering both tectonic and stratigraphic data, is that the same fault zone seems to have a larger left-lateral component during Tortonian and the stress field gradually changed during Messinian, when the normal component dominates, increasing the compatibility of the stress field with arc-parallel extension. The latter seems to be active up to the contemporary era and is tectonically responsible for the Arkalochori earthquake.