Adjoint Tomography of the Middle East

The Middle East is a diverse tectonic region combining all three types of plate boundaries and several geological settings. The Owen Fracture Zone, to the East of the Arabian Plate, is parallel to the Masirah Transform Fault and connects the Murray, East Sheba, and Carlsberg Ridges. The Gulf of Aden, to the South, separates the Arabian and African Plates. The Red Sea Spreading Center, located southwest, separates the Nubian and Arabian Shields. The Red Sea is an example of a newly formed oceanic basin, and it is part of the Cenozoic Afro-Arabian Rift System. The Dead Sea Transform Fault extends northeastwards until the complex convergent boundary with the Anatolian and Eurasian Plates, to the North. To the Northeast, the Zagros suture zone accommodates the deformation from the convergence of the Arabian and Eurasian Plates, raising the Zagros Mountains and uplifting the Iranian Plateau. To have better insight into the region's complex geological and tectonic processes, we perform a continental-scale adjoint inversion of the Middle East based on 3D spectral-element simulations. We use a dataset of about 250 earthquakes from the CMT catalog recorded by permanent and temporary broadband seismometers, including the regional networks such as those from the Saudi Geological Survey, Kandilli Observatory etc. We discard noisy components and select usable seismogram sections using the PyWinEPAdjoint toolbox (Ciardelli et al., 2021). We use exponentiated-phase measurements (Yuan et al. 2020), an objective function that extracts the phase information from every wiggle in selected measurement windows. We present our preliminary results of our adjoint model for the lithosphere and the upper mantle beneath the Middle East region.