Co-seismic Deformation and Structural Controls of the 3 August 2026 Mw 5.6 Suez Earthquake, Egypt, from Sentinel-1 InSAR, Seismicity and Satellite Gravity

Abstract One of the greatest instrumentally recorded occurrences in the Cairo-Suez area was the Mw 5.6 earthquake on August 3, 2026, which occurred north of Suez near the northern end of the Suez Rift. We investigate its surface deformation and structural setting by integrating Sentinel-1 interferometric synthetic aperture radar (InSAR), seismicity, focal-mechanism information and satellite-only gravity data. Co-seismic interferograms from ascending Track 160 (22 July–3 August 2026) and descending Track 94 (24 July–5 August 2026) were processed with GMTSAR, supplemented by ascending Track 58 and a pre-event LiCSAR interferogram (frame 094D_05947_131210). The processed fields show maximum line-of-sight (LOS) displacements of ~ 4 cm (ascending) and ~ 3 cm (descending) around the epicentral area, superimposed on long-wavelength components; the fault-localized LOS step across the nearest mapped fault is ~ 7 mm. Decomposition of the two geometries yields E–W and vertical components of up to ~ 2.5 cm and ~ 3.05 cm, respectively. A pre-event interferogram shows only a weak, spatially limited anomaly that cannot be regarded as precursory. Seismicity and the focal-mechanism solution indicate predominantly normal faulting on a NW–SE-striking plane (strike ~ 326°, and 152°, dips of 35° and 55°) in the integrated model). Gravity data reveal a density boundary near the epicenter, with SI = 1 Euler solutions yielding a median depth of 14.8 km and a dominant NNW–SSE trend (338°/158°). These findings agree with the regional rift orientation and the InSAR-derived fault depth of 17.6 km. The spatial agreement between deformation, seismicity and gravity-derived structures suggests that the earthquake ruptured a pre-existing rift-related structure, providing new constraints on active deformation and seismic hazard in the northern Suez Rift.