## 3 Results
### Relative Locations (hypoDD) of the Seismic Catalogue
In area 3 (Matala), most of the events that were relocated using hypoDD belong to the earthquake sequence that occurred near Matala between 17 May 2023 and 31 May 2023. More than 130 events were located using the local velocity model obtained using the data of this study, achieving a better concentration near some of the most significant local fault sources [13; 52] as a first result. The calculation of differential travel times resulted in an average number of five links per event pair and average offset between linked events of 2.07 km. The earthquakes of the relocated catalogue are mainly concentrated in between the E-W striking, north (Siva fault) and south (Gortyna fault) dipping normal faults 2 km east of Matala (supplementary material). The majority of the events of sub-region 4 (Heraklion, Central Crete) belong to the 2021-2022 Arakalochori earthquake sequence. The 27 September 2021 mainshock (Mw = 6.0) was preceded by 300 events of M\({}_{\rm L}\geq 2.2\) in the area between the Galatas and Avli normal faults in the area S-SE of Heraklion city. The epicentre of the mainshock was located less than 5 km to the SE of Arkalochori (lat: 35.1433\({}^{\circ}\) N, long: 25.2688\({}^{\circ}\) E) at a depth of \(\sim\)9.5 km, slightly different from that of [63; 64; 65]. The denser cluster of events is located  
Figure 9: Histogram of the depth distribution of the relocated catalogue. west of the mainshock in an approximately 15 km long area associated with the foreshocks (June-September 2021). A significant cluster can be seen in the region between the Amourgeles and Parthenio N-S striking normal faults, while to the NE, a major group of events is concentrated in the football of the Agnos NE-SW-oriented normal fault near the town of Kastelli (supplementary material). The majority of the focal depths are between 4 and 16 km. In the area of SE Crete-Pliny Trench (sub-region 5), the results show small (or no) improvement in the relocation process due to the greater distance of the nearest station and the large azimuthal gap of the initial location data. Most seismic events of the initial catalogue are concentrated in clusters along the Cretan and the Pliny Trench south of Crete. In this application, a significant portion of the initially located seismic catalogue is eliminated from the relocated data due to the absence of nearby stations. In the area of Zakros-Karpathos (sub-region 6), 799 out of 832 events of the initial catalogue (M \(\geq\) 2.2) were relocated with hypoDD, improving the concentration of the earthquakes along the main local and regional fault zones (supplementary material). The calculation of differential travel times resulted in an average number of eight links per event pair and average offset between linked events of 2.39 km. Seismicity was divided into some smaller clusters that are characterised by a range of hypocentral depth. Specifically, earthquakes of intermediate depth (32 \(\leq\) H(km) \(\leq\) 50) are detected both in Karpathos (\(\sim\)10 km N of Kasos), east and north of Agios Nikolaos, and in the Cretan Sea to the north (\(\sim\)50 km NNE of Agios Nikolaos). Accordingly, surface earthquakes are located near the fault that defines the eastern end of Mirabello Gulf and Sitia (\(\sim\)20 km NNW of Zakros), with depths ranging from 3.5-21 km. Furthermore, six (6) cross-sections were performed in order to see the impact of the relocation procedure on the sequence hypocentral depths and the discrimination of the local activated structures (Figure 10). Cross-sections 1-2 (A-A\({}^{\prime}\), B-B\({}^{\prime}\)) have an E-W and NNE-SSW orientation, respectively. Cross-section A-A\({}^{\prime}\) covers the study areas from Antikythera to Karpathos Island in an E-W direction, cutting the main N-S striking offshore normal faults of the Cretan Sea. In this section, the dip angle differs from one corner of the study area to the other.