Updated seismotectonic framework of Abu Dabbab Egypt based on focal mechanisms and stress inversion

The Abu Dabbab seismic zone is located along Egypt's Red Sea margin, stands out as one of the most active seismic regions in the Eastern Desert. Characterized by frequent micro earthquakes, swarm like activity, and notable historical events. To enhance understanding of its tectonic framework, 408 earthquakes (Ml 0.7-3.0) recorded in 2004 were analyzed using digital waveform data from a temporary local seismic network consisting of ten vertical short period seismometers. Focal mechanisms were determined from P-wave first-motion polarities and classified using ternary plots. The analysis revealed a diverse range of faulting styles normal, strike slip, reverse, and oblique with clear depth dependent patterns. Shallow events (0-5 km) were dominated by normal and strike slip faulting, intermediate depths (5-10 km) showed increased reverse and oblique components, while deeper events (> 10 km) were primarily normal faulting. Stress tensor inversion across three depth intervals indicated a multiphase stress regime: shallow depths exhibited alternating faulting styles due to localized stress variations; intermediate depths revealed a heterogeneous stress field with mixed faulting regimes; and deeper levels showed a dominant normal faulting regime, consistent with the extensional tectonics of the Red Sea Rift. Overall, the stress field is shaped by NE-SW compression and SE-NW extension, with deformation concentrated along NW-SE and NE-SW trending faults. These findings underscore the combined influence of regional rift-related extension and local factors such as magmatic intrusions and crustal heterogeneity in driving seismicity at Abu Dabbab. This study yields important insights into depth dependent stress patterns and active faulting, enhancing seismic hazard assessments and highlighting the region's potential as a sustainable geothermal energy source within a tectonically dynamic environment.