Complex Coseismic and Postseismic Faulting During the 2021 Northern Thessaly (Greece) Earthquake Sequence Illuminated by InSAR Observations

Abstract

As one of the most seismically active areas in central-northern Greece, Thessaly has been undergoing nearly N-S oriented crustal extension since Late Miocene, forming several prominent basin-and-range landforms such as Tyrnavos basin and Antichasia mountain (Caputo & Pavlides, 1993, Figure 1). Around the primary geologic-tectonic structure, there develop a series of parallel or subparallel synthetic and antithetic normal faults which control the overall tectonic environment of the broader Thessaly area (Figures 1b, 1e and 1g, Mavroulis et al., 2021). In terms of the geographical distribution of these active faults, they are generally grouped into two main fault zones, namely, the southern and northern Thessaly fault zone (SFZ and NFZ), respectively, where the seismicity mainly occurs (Figure 1b). However, compared with that the recent large earthquakes (M W > 6.0) are mainly concentrated in the SFZ, the scarcity of large historical events in the NFZ presents a seismic gap (Caputo, 1995, Figures 1b and 1c), which hinders our understanding of the regional strain accumulation and seismogenic structure. Moreover, simultaneous multi-failure in a single large earthquake often leads to higher hazard than that caused by the delayed failure of multiple faults in a seismic sequence which spans a long period of hours to years (e.g., Walters et al., 2018). But our knowledge of whether multi-failure occurs simultaneously in seconds or protracted

A Deeper Look Into the 2021 Tyrnavos Earthquake Sequence (TES) Reveals Coseismic Breaching of an Unrecognized Large‐Scale Fault Relay Zone in Continental Greece

“…The epicentral region of the TES is well monitored instrumentally by an abundance of permanent/temporary seismic and GNSS stations (Figure 2), while InSAR allowed the quantification of the coseismic displacements associated with each of the main events (i.e., Ganas et al., 2021; Papadopoulos et al., 2021). Using a combination of seismological, geodetic and InSAR data, numerous studies attempted to kinematically model the rupture sequence, proposing either a two (Karakostas et al., 2021), a three (Ganas et al., 2021; Kassaras et al., 2022; Papadopoulos et al., 2021) or a four (De Novellis et al., 2021; Yang et al., 2022) fault source model. Despite the differences, all proposed models agree on the geometry and approximate location of the fault that produced the large (M w 6.3) March 3rd earthquake.…”

A Deeper Look Into the 2021 Tyrnavos Earthquake Sequence(TES) Reveals Coseismic Breaching of an UnrecognizedLarge-Scale Fault Relay Zone in Continental Greece

“…The epicentral region of the TES is well monitored instrumentally by an abundance of permanent/temporary seismic and GNSS stations (Figure 2), while InSAR allowed the quantification of the coseismic displacements associated with each of the main events (i.e., Ganas et al, 2021;Papadopoulos et al, 2021). Using a combination of seismological, geodetic and InSAR data, numerous studies attempted to kinematically model the rupture sequence, proposing either a two (Karakostas et al, 2021), a three (Ganas et al, 2021;Kassaras et al, 2022;Papadopoulos et al, 2021) or a four (De Novellis et al, 2021;Yang et al, 2022) fault source model. Despite the differences, all proposed models agree on the geometry and approximate location of the fault that produced the large (M w 6.3) March 3rd earthquake.…”

Space Geodetic Views on the 2021 Central Greece Earthquake Sequence: 2D Deformation Maps Decomposed From Multi-Track and Multi-Temporal Sentinel-1 InSAR Data

“…Novellies et al [28] also used InSAR technology to studied this earthquake sequence, and their results confirmed the NE dipping direction of the second event. Yang et.al [3] studied this earthquake sequence using co-seismic and early post-seismic InSAR data. Their results support the NE dipping direction of the second event.…”

“…Previous researches reported that the well-known and -studied faults in Central Greece did not generate this earthquake sequence [1]. These earthquakes are likely to occur on unmapped or named as blind faults [2,3]. Determining the fault geometry of these blind faults is the significant premise for studying earthquake physics and understanding regional seismogenic mechanism [4,5].…”

“…This is because an Pioneering research on the 2021 central Greece (Thessaly) earthquake sequence inverted 2D deformations of total three earthquakes using two interferograms of T80 and T175 (02 Mar 2021 -14 Mar 2021) [1]. The inverted 2D deformation maps contain the cumulative co-seismic deformations of three earthquakes and early post-seismic deformations [3]. Subsidence dominates the maximum displacement in UD, and a small cumulative uplift locates around the subsidence.…”