<span style="mso-ansi-language: EN-GB;">The Afghanistan Earthquake of 21 June, 2022: The Role of Compressional Step-Overs in Seismogenesis

The Afghanistan earthquake of 21 June 2022 occurred on an ~10 km-long fault segment of the North Waziristan&ndash;Bannu Fault system (NWBFS) located towards the north of the Katawaz Basin. The earthquake was a shallow event that reportedly caused widespread devastation across the affected region. In this note, we investigated the long-term, i.e. geological and geomorphological evidence of deformation along the earthquake segment. For comparison, we also studied the short-term space geodetic and remote sensing results documenting a visible offset between the fault traces observed based on the two different methodologies. Focusing on the fault modelling and on published results, it is thus clear that the earthquake rupture did not reach the surface, instead it stopped in the shallow sub-surface at ~1 km-depth. Moreover, the InSAR analyses show some technical issues such as coherence loss etc., likely due to severe ground shaking leaving some gaps in the results; geological and geomorphological evidence complemented this information and contributed to filling these gaps. As a further outcome of this research, we confirm that the InSAR results could generally capture the overall fault geometry at depth even in case of blind faulting, whereas the detailed geometry of the tectonic structure, in this case with a right stepping en-echelon pattern could be successfully captured by the geological and geomorphological approaches and optical remote sensing observations. Accordingly, the right stepping along the major reactivated fault generates a restraining bend in the dominantly left-lateral crustal shear zone. Therefore, such fault stepovers are capable of localizing strain and could act as loci for seismic ruptures bearing strong implications for the seismic hazard assessment of the region as well as of other strike-slip fault zones.