On the driving forces of the rifting processes along the Makkah-Madinah Transform Zone, Western Arabia

The Arabian Margin experienced intense volcanism over the last 10 Ma, including volcanic eruptions as recent as 600 years ago. What is more, two earthquakes with magnitude > 5 have been recently reported with normal faulting along the Arabian Margin, suggesting that the Arabian Margin is undergoing active deformation. Due to the limited number of GPS stations within the Arabian plate, investigating the intraplate deformation was challenging. A new set of GPS data with 87 stations is used in this work to investigate the Arabian margin rigidity and intraplate deformation (Aldaajani et al., 2021). This new GPS velocities show higher residuals along the Arabian margin that produces dilatational strain rate pattern within the Arabian margin, in the vicinity of the Makkah-Madinah Transtensional zone. The causes of these GPS residuals along the Arabian Margin are unknown. In this work, we use the finite element modeling approach to highlight the mechanical deformation processes along the Arabian margin and test their driving forces. These candidate forces are related either to the edge forces as introduced by the Red Sea rift, the Arabian Margin interior forces as introduced by calculating the Gravitational Potential Energy, or the basal tractions as driven by sub-lithospheric topography and mantle flow. Our results indicate that the GPS residuals are not likely linked with the Gravitational Potential Energy forces. Instead, the basal tractions along an asthenospheric channel, which aligns geographically with the Makkah Madinah Volcanic Line, is the potential driving force for the observed deformation along the Arabian margin.