GPS Geodesy Experiments in the East African Rift

D. Sarah Stamps, Eric Calais, Elifuraha Saria, Lucy M. Flesch, Daniel Koehn, Laura Bennati, Haylee Dickinson

The East African Rift (EAR), spanning more than 6,000 km N-S and 2,000 km E-W, is the Earth’s major divergent plate boundary separating the Nubian and Somalian plates. Although the process of continental rifting is of primary importance to seismic and volcanic hazards, ocean formation, and vital natural resources, the underlying physics remains debated. A first step towards understanding the dynamics of the EAR is identifying the geometry and relative plate motions. Plate motions and strain distribution along and across diverse rift settings, measurable from GPS observations, is a key data set required to elucidate the kinematics and dynamics of continental rifting.

We present four projects that utilize GPS geodesy to address key questions about continental rifting: 1) Constraints on mantle-lithosphere interactions in East Africa, 2) Structural expression of extreme rift-flank uplift, 3) Kinematic constraints on the Lwandle-Somalian plate boundary, and 4) Magma-tectonic processes in an active transitional rift from seismic, GPS, and modeling studies in Afar. GPS observations span the Afar region in the northern part of the EAR, the central EAR from the western branch in Uganda to the eastern branch in Tanzania and eastward to the continental island of Madagascar.