Five years of continuously recording GPS observations in the Kingdom of Saudi Arabia together with new continuous and survey‐mode GPS observations broadly distributed across the Arabian Peninsula provide the basis for substantially improved estimates of present‐day motion and internal deformation of the Arabian plate. We derive the following relative, geodetic Euler vectors (latitude (°N), longitude (°E), rate (°/Myr, counterclockwise)) for Arabia‐Nubia (31.7 ± 0.2, 24.6 ± 0.3, 0.37 ± 0.01), Arabia‐Somalia (22.0 ± 0.5, 26.2 ± 0.5, 0.40 ± 0.01), Arabia‐India (18.0 ± 3.8, 87.6 ± 3.3, 0.07 ± 0.01), Arabia‐Sinai (35.7 ± 0.8, 17.1 ± 5.0, 0.15 ± 0.04), and Arabia‐Eurasia (27.5 ± 0.1, 17.6 ± 0.3, 0.404 ± 0.004). We use these Euler vectors to estimate present‐day stability of the Arabian plate, the rate and direction of extension across the Red Sea and Gulf of Aden, and slip rates along the southern Dead Sea fault south of the Lebanon restraining bend (4.5–4.7 ± 0.2 mm/yr, left lateral; 0.8–1.1 ± 0.3 mm/yr extension) and the Owens fracture zone (3.2–2.5 ± 0.5 mm/yr, right lateral, increasing from north to south; 1–2 mm/yr extension). On a broad scale, the Arabian plate has no resolvable internal deformation (weighted root mean square of residual motions for Arabia equals 0.6 mm/yr), although there is marginally significant evidence for N‐S shortening in the Palmyride Mountains, Syria at ≤ 1.5 mm/yr. We show that present‐day Arabia plate motion with respect to Eurasia is consistent within uncertainties (i.e., ±10%) with plate tectonic estimates since the early Miocene when Arabia separated from Nubia. We estimate the time of Red Sea and Gulf of Aden rifting from present‐day Arabia motion, plate tectonic evidence for a 70% increase in Arabia‐Nubia relative motion at 13 Ma, and the width of the Red Sea and Gulf of Aden and find that rifting initiated roughly simultaneously (±2.2 Myr) along the strike of the Red Sea from the Gulf of Suez to the Afar Triple Junction, as well as along the West Gulf of Aden at 24 ± 2.2 Ma. Based on the present kinematics, we hypothesize that the negative buoyancy of the subducted ocean lithosphere beneath the Makran and the Zagros fold‐thrust belt is the principle driver of Arabia‐Eurasia convergence and that resisting forces associated with Arabia‐Eurasia continental collision have had little impact on plate motion.

International audienceGPS measurements adjacent to the southern Red Sea and Afar Triple Junction, indicate that the Red Sea Rift bifurcates south of 17 degrees N latitude with one branch following a continuation of the main Red Sea Rift (similar to 150 degrees Az.) and the other oriented more N-S, traversing the Danakil Depression. These two rift branches account for the full Arabia-Nubia relative motion. The partitioning of extension between rift branches varies approximately linearly along strike; north of similar to 16 degrees N latitude, extension (similar to 15 mm/yr) is all on the main Red Sea Rift while at similar to 13 degrees N, extension (similar to 20 mm/yr) has transferred completely to the Danakil Depression. The Danakil Block separates the two rifts and rotates in a counterclockwise sense with respect to Nubia at a present-day rate of 1.9 +/- 0.1 degrees/Myr around a pole located at 17.0 +/- 0.2 degrees N, 39.7 +/- 0.2 degrees E, accommodating extension along the rifts and developing the roughly triangular geometry of the Danakil Depression. Rotating the Danakil Block back in time to close the Danakil Depression, and assuming that the rotation rate with respect to Nubia has been roughly constant, the present width of the Danakil Depression is consistent with initiation of block rotation at 9.3 +/- 4 Ma, approximately coincident with the initiation of ocean spreading in the Gulf of Aden, and a concomitant similar to 70% increase in the rate of Nubia-Arabia relative motion

The Afar Depression, at the northern end of the East African Rift, is the only place on land where the transition from a plumeinduced continental breakup to seafl oor spreading is active today. New images of seismic velocity structure, based on exceptional new data sets, show that the mantle plume that initiated rifting in Africa is absent beneath Afar today. The images are dominated by a major low-velocity feature at ~75 km depth closely mimicking the abrupt changes in rift axis orientation seen at the surface. This is likely associated with passive upwelling beneath the rift. Additional focused low-velocity anomalies show that small diapiric upwellings are present beneath major off-axis volcanoes. These multiple melting sources can explain the wide range of geochemical signatures seen in Afar. These images suggest that passive upwelling beneath Afar marks the initiation of rift segmentation as continental breakup progresses to seafl oor spreading.

Local and regional seismic data constrain the space‐time history of deformation and likely magma sources for the September 2005 diking episode in the Manda‐Harraro rift zone of the Afar depression. The results distinguish three centers from which subhorizontal dike propagation progressed: two distinct sources around the Dabbahu‐Gab'ho Volcanic Complex (DVC) and the third at the Ado'Ale Volcanic Complex (AVC). The temporal development of seismicity shows that the majority of the dike volume is fed from beneath AVC and migrated laterally with an average rate of 15–30 cm/sec. This dike emplacement at a divergent plate boundary is unusual due to the rapid intrusion of a large volume of magma and the large amount of seismic moment release. We interpret this volcano‐tectonic crisis as a complex interaction of multiple magma plumbing sources and lithosphere at a plate boundary under extension. Such repeated episodes will eventually shape the incipient oceanic rift morphology.