In the vicinity of the study area, two major historical earthquakes have been reported (Figure 1). The first is the 1 July 1494 (\(M\) = 5.4) earthquake [15] that occurred close to Heraklion and caused damage to church towers and private buildings, while large waves were observed in the harbor [22]. One century later, on 26 November 1595, another earthquake (\(M\) = 6.4) took place a few kilometers off the Heraklion city, causing severe damage and destruction in the entire Crete island [15; 22]. It is worth noticing that no large events (\(M\)\(\geq\) 6.0) occurred in the study area during the instrumental period (after 1900), with the nearest one being recorded on 23 May 1994 (\(M_{\rm w}\) = 6.1) and that was an intermediate depth (60-70 km) event (Figure 1b) located approximately 40 km WNW of Heraklion [16]. [PERSON] [24] assessed the seismic hazard for the three largest cities of Crete and obtained maximum peak ground acceleration (PGA) values for Heraklion between 0.130 g and 0.165 g for rock and soft soil conditions, respectively. One of the major structures that seem to control the HB-MB complex is the NNE-SSW fault zone that controls its eastern margin, located only a few kilometers east of Arkalochori village (Figure 2). It bounds the easternmost post-Alpine sediment outcrops of the HB-MB in a morphologically clear way, even though several active structures seem to intersect. It was only recently (27 September 2021) that the lethal \"Arkalochori earthquake\" occurred in this area, causing one fatality, and resulting in hundreds of damaged buildings, mainly of old stone-built masonry. As the authorities reported, more than 6150 houses have been declared uninhabitable due to excessive damage in the mainly affected municipality of Minoa Peidiadas (Figure 1), as a result of the mainshock and the major aftershocks. The earthquake of 27 September 2021, 06:17:21 UTC, occurred near Arkalochori, Central Crete, ~25 km SSE of Heraklion city [25; 26]. Its focal mechanism is characterized by an SSW-NNE to SW-NE-trending, nearly dip-slip normal faulting. Considering the solutions proposed by different agencies (Table S1), except for a few outliers, its strike generally ranges N200\({}^{\circ}\) E-N230\({}^{\circ}\) E and its dip angle varies between 40\({}^{\circ}\) and 60\({}^{\circ}\). The magnitude of the main event was initially determined as \(M_{\rm L}\) = 5.8 by the Seismological Laboratory of the National and Kapodistrian University of Athens (SL-NKUA) and the Geodynamic Institute of the National Observatory of Athens (GI-NOA), but later measurements of seismic moment upgraded its value to \(M_{\rm w}\) = 5.9-6.0. The largest aftershock (\(M_{\rm w}\) = 5.3) occurred on 28 September 04:48:08 UTC, one day after the mainshock, with a similar focal mechanism. According to the report of ITAK [27], the recorded PGA at station ARK1 in the epicentral area (Arkalochori) was 609 cm s\({}^{-2}\) in the horizontal component (N-S) and 806 cm s\({}^{-2}\) (~0.82 g) in the vertical one, with the duration of strong ground motion (~0.1 g) being 6 s. The horizontal to vertical spectral ratio reached 8 at the dominant frequencies of 0.65 Hz and 1.4 Hz. The accelerometric recordings at station ARK1 far exceeded the provisions of the National Building Code [28] for effective PGA = 0.24 g at the epicentral region in the seismic hazard zone II and for soil classes A and B.  
Herein, we present a multi-disciplinary work, based on extensive fieldwork and detailed geological mapping of the affected area at central Crete, combined with results from seismological and geodetic imaging techniques. Our aim is to understand the contemporary seismotectonic regime of a densely populated area close to the active Hellenic arc and provide useful data for a realistic model concerning the neotectonic evolution of Crete. We intend to examine whether arc-parallel extension is a temporal phenomenon that is related to the Arkalochori earthquake or a dominant contemporary stress component.