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

Pioneering efforts well studied the deformation decomposition of single earthquake using a pair of ascending (ASC) and descending (DES) track interferometric synthetic aperture radar (InSAR) data. However, deformation decomposition of sequent events is rarely discussed and hard to implement. That's because it's hard to ensure deformations related to each earthquake can be recorded by a pair of ASC and DES track data. Three sequent earthquakes (Mw>5.5) just hit Central Greece in March 2021, and this earthquake sequence provides us with a perfect case to study 2-D (east-west and up-down) deformation decomposition when the mentioned premise cannot be satisfied. In this context, we proposed a Multi-track and Multi-temporal 2-D (MTMT2-D) method. Its novelty and behind rationale are to decompose 2-D deformations of each event through fusing multitrack and multitemporal interferograms. Based on the decomposed deformations, we invert the slip distribution of three earthquakes respectively. We found that the decomposed deformations can better constrain the fault geometry than the single InSAR interferogram. Furthermore, our geodetic inversion results also suggest a domino-like triggering rupture process for this earthquake sequence. It indicates that our MTMT2-D method can potentially reveal more details about earthquake sequence.