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

Large magnitude (Mw ∼ ≥6) earthquakes in extensional settings are often associated with simultaneous rupture of multiple normal faults as a result static and/or dynamic stress transfer. Here, we report details the coseismic breaching previously unrecognized large-scale fault relay zone central Greece, through three successive moderate 5.7–6.3) that occurred over period ∼10 days March 2021. Specifically, joint analysis InSAR, GNSS and seismological data, coupled detailed field digital mapping, reveals Tyrnavos Earthquake Sequence (TES) was accommodated at northern end ∼100 km wide transfer structure, by largely unbroken during Holocene. By contrast, southern section this appears to have accrued significant slip InSAR-derived displacements agree loci eight subtle, undetected, syn-seismic TES. Kinematic modeling mapping suggests all involved interconnected depth, their conjugate fault-intersections acting barriers propagation. We also find TES mainshocks were characterized unusually high (>6 MPa) stress-drop values scale inversely length earthquake magnitude. These findings, collectively suggest propagated north-westward increasingly stronger asperities intersections, transferring between tips well-established, but unrecognized, structure. Fault zones may be prone elevated seismic hazard.