Interseismic Deformation in the Gulf of Aqaba Inferred from GPS Measurements

Abstract

<p>The Dead Sea Transform fault forms the boundary between the Arabian plate and the Sinai-Levant subplate. Several aspects of this fault system have been extensively studied during the last century. However, the present-day kinematics and deformation along its southern end in the Gulf of Aqaba remain poorly understood. Here we present a crustal motion velocity field based on three GPS surveys conducted between 2015 and 2019 at 30 campaign sites, complemented by 12 permanent stations operating near the gulf. We constrained a pole of rotation for the Sinai-Levant subplate based on five selected stations on the Sinai Peninsula. This Euler pole predicts a left-lateral slip rate of ~4.5 mm/yr on the fault system in the gulf, consistent with earlier findings. We find that standard models of interseismic deformation, such as back-slip and screw dislocation models do not provide a reasonable constraint on fault locking depths due to limited near-fault measurements. Despite this, our results reveal a small (~1 mm/yr) but systematic left-lateral residual motion across the gulf that cannot be resolved by elastic models of strain accumulation. We further find that the orientation of these residuals agrees with modelled postseismic transient motions caused by the 1995 M<sub>W</sub> 7.2 Nuweiba earthquake in the NE and SW quadrants relative to the gulf trend. Combined, these observations suggest that postseismic deformation caused by the Nuweiba earthquake may still be ongoing. We anticipate our findings to be a starting point for future geodetic studies in the northern Red Sea region where large-scale infrastructure mega-projects, such as the NEOM city and the King Salman bridge across the gulf are being developed. Future studies would benefit from incorporating additional GPS stations on the Sinai side of the gulf, refined finite-fault models, seafloor geodetic measurements and better information about past earthquakes.</p>