The co-seismic and post-seismic deformation field associated with the M5.9 Arkalochori main shock that occurred in central Crete (Greece) on 27 September 2021 is analyzed using Copernicus Sentinel-1A & 1B images, GNSS measurements and seismological data. The fault geometry is constrained through the joint inversion of multiple datasets and the slip distribution for the co-seismic and post-seismic period is obtained using a homogeneous half-space elastic model and the Steepest Descent Method. The results indicate a blind normal fault striking 215° with a 55° dip to the northwest and the co-seismic slip model suggests a nearly circular main slip patch (8 × 6 km) with a maximum slip of 0.98 m. Post-seismic displacements started rapidly after the main shock followed by a gradual decay as highlighted by the calculated InSAR time series. The temporal evolution of post-seismic slip is described by a simple logarithmic function, decaying faster at the southwest part of the fault. The cumulative afterslip model suggests that the maximum post-seismic slip of 0.23 m occurred within a similar depth range compared to the co-seismic one, yet with a shift towards the southwest. Post-seismic slip inside the main shock rupture area is sustained, highlighting the slow recovery of locking in the co-seismic slip region. Afterslip (seismic or aseismic) played a dominant role in the early post-seismic period acting complementarily to the main rupture. Indications suggest that the spatiotemporal evolution of the productive aftershock sequence may be driven afterslip, alongside other potential factors.

中文翻译：

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受大地测量数据和余震约束，与 2021 年克里特岛中部（希腊）Mw5.9 Arkalochori 地震相关的同震和震后滑动


使用哥白尼 Sentinel-1A 和 1B 图像、GNSS 测量和地震数据分析了 2021 年 9 月 27 日在克里特岛中部发生的 M5.9 Arkalochori 主震相关的同震和震后形变场。通过多个数据集的联合反演来约束断层几何形状，并使用齐次半空间弹性模型和最速下降法获得同震和震后时期的滑移分布。结果表明，存在一条 215° 的盲正断层，向西北倾斜 55°，同震滑移模型表明存在一个近圆形的主滑移带（8 × 6 km），最大滑移为 0.98 m。正如计算的 InSAR 时间序列所强调的那样，震后位移在主震后迅速开始，随后逐渐衰减。震后滑移的时间演化通过简单的对数函数来描述，在断层的西南部分衰减得更快。累积后滑模型表明，与同震相比，最大震后滑移发生在相似的深度范围内，为 0.23 m，但向西南方向移动。主震破裂区内的震后滑移持续存在，凸显了同震滑移区锁定的缓慢恢复。余滑（地震或抗震）在震后早期起主导作用，与主破裂相辅相成。有迹象表明，余震序列的时空演化可能是由后滑以及其他潜在因素驱动的。