The Arkalochori Mw = 5.9 Earthquake of 27 September 2021 Inside the Heraklion Basin: A Shallow, Blind Rupture Event Highlighting the Orthogonal Extension of Central Crete

A strong, shallow earthquake occurred near Heraklion (Crete, Greece) on 27 September 2021. The produced significant ground deformation in the vicinity of Arkalochori village but without any evidence for surface ruptures primary origin. We used geodetic (InSAR and GNSS) data to map motions Earth’s that during shortly after earthquake. 14 cm subsidence GNSS station ARKL a maximum 19 distance from SAR satellite were recorded. measured displacements constrain rupture geometry slip distribution at depth. Our best-fitting inversion model suggests 13 km-long planar normal fault striking N195° E dipping 55° northwest, with major occurring east updip hypocentre. tip is located 1.2 km beneath surface. coseismic uppermost crust, depth interval 4–6 km. decrease offsets toward likely caused by an increased frictional resistance layers rapid slip. Satellite observations made first month detected no post-seismic (i.e., below one fringe or 2.8 cm). seismic may be identified Avli (Lagouta) segment NNE-SSW striking, west-dipping, 23 neotectonic Kastelli Fault Zone (KFZ). Part along segment, indicating linkage history overlapping KFZ. Based geological footwall topography we estimate average rate between 0.17–0.26 mm/yr paradigm example on-going extension basin (central Crete) WNW-ESE direction, which almost orthogonal E-W Messara graben other active faults south coast Crete.