Influence of Geological and Geomorphological Factors on Vertical Co-Seismic Deformation Induced by the Mw 7.2 Al Haouz Earthquake (Morocco, 2023)

Abstract. This study analyzes the influence of structural, lithological, and geomorphological factors on vertical co-seismic deformation caused by the Mw 7.2 Al Haouz earthquake of 8 September 2023 in Morocco. Vertical deformation, derived from Differential InSAR analysis of Sentinel-1A imagery, was compared with lithological units, fault structures, and terrain attributes extracted from the FABDEM digital elevation model, including slope, aspect, and geomorphon-based landform classes. Results show that deformation was strongly controlled by geology. Cambrian shaly formations, known for their plasticity and instability, exhibited the highest vertical displacements. Proximity to faults also enhanced deformation, with a 1000 m buffer around mapped faults yielding mean uplift of 5.3 cm (SD = 5.4 cm) and deformation gradients averaging 1.02% (SD = 1.8%). Topography played a significant role. Flat areas (<5°) generally subsided (–2.6 cm), while steeper slopes showed uplift, peaking at 5.4 cm near 45°. Slope orientation influenced deformation distribution: northeast-, east-, southeast-, and south-facing slopes recorded uplift (1.5–3.2 cm), whereas north- and northwest-facing slopes and flats showed subsidence (–0.9 to –1.6 cm). Landform analysis revealed systematic variations. Subsidence dominated flat, shoulder, and footslope forms, while uplift prevailed in pits, hollows, spurs, ridges, and peaks. Spurs in particular displayed strong deformation (mean uplift: 2.9 cm, SD = 10.6 cm), with ~11% of deformation boundaries coinciding with spur boundaries, suggesting they act as structural controls on rupture propagation. Overall, the findings demonstrate that lithology, faulting, and terrain morphology jointly modulate co-seismic deformation. Integrating DInSAR with terrain analysis provides valuable insights into earthquake surface processes and spatial hazard assessment.