State of stress and stress rotations: Quantifying the role of surface topography and subsurface density contrasts in magmatic rift zones (Eastern Rift, Africa)

In rift settings, the crustal stress field is dominated by extension, which leads to rift-parallel topography and basin alignments. However in some continental systems, observables of orientation principal stresses show substantial deviations from these patterns. Such rotations are currently poorly understood could reflect critical role magmatism creation topography, plate state-of-stress, volcanic tectonic processes. Yet magma intrusions, thinning, flank on zone remain quantified. The seismically- volcanically-active Magadi-Natron-Manyara region East African Rift shows a 60 ∘ local rotation with respect regional extension. Here, we test hypothesis that such due cumulative effects surface subsurface loads (lateral density contrasts). We use analytical calibrated numerical models magmatic zones simulate lithospheric deformation presence bodies, quantify their effect intrusions fault kinematics setting. Our 3D static weakly extended suggest influences shallow localization, whereas contrasts play larger lower localization. Both patterns preferred for melt storage beneath valley. interaction between pressurized reservoir generate orientations consistent observed earthquake focal mechanisms. results demonstrate how geometry thinning can guide strain highlighting need three-dimensional treatment kinematics. • Surface Subsurface Topography, subsurface, extension produce rotation. important complete spatial understanding tectonics.